If anyone is interested in more in-depth reading about bird responses to artificial playback of sounds, there is a somewhat sparse, but interesting, body of scientific literature (I haven't read all this, just highlighting a couple bits):



"Pishing and playback treatments altered bird behavior in similar ways; both increased vocalization behavior and decreased foraging and movement behaviors (Figure 3). Pishing also reduced self-maintenance behaviors, tending to induce more dramatic and prolonged changes in vocalization behavior than did playback, and reduced foraging for a longer period than did playback (Figure 3). Pishing is thought to increase the detectability of birds by inducing a generalized mobbing response in the birds that hear it (Zimmerling and Ankney 2000, Langham et al. 2006). Because pishing induces a generalized response in bird communities (Langham et al. 2006), more species are likely to respond to pishing (Zimmerling and Ankney 2000, Zimmerling 2005, Langham et al. 2006) than would respond to a species-specific song. Although we did not consider the response of different species during the observation periods, the behavioral response to playback may have been driven primarily by cardinals, whereas the response to pishing is likely to have been driven by the response of multiple species. This may explain why pishing altered more behaviors and some behavioral categories for a longer period of time than did playback. Additional research that follows the responses of different species to pishing and playback is needed to assess this possibility. Playback of predator calls could induce a mobbing response in some species (Lynch 1995, Wilkins and Husak 2006); however, we used eastern screech-owl song during playback exposure only once and after we played northern cardinal songs. Birds may have a stronger response to repeated predator song playback, and this also warrants further investigation.
Potentially, the behavioral changes observed in all simulated birder exposures could reduce the probability of overwinter survival, with the greatest potential for negative impacts found in the pishing treatment and the least in the birder treatment. Altered vocal activity may indicate increased stress (Harris and Haskell 2013), aggression (Amy et al. 2010, Jacobs et al. 2014), or fear (De Haas et al. 2012) and could increase energy mobilization through activation of the hypothalamic-pituitary-adrenal axis (i.e., stress response; Wingfield et al. 1998). Additionally, vocal activity can attract and expose individuals to predators (Millard et al. 2011). Reduced foraging activity implies that birds spent less time gathering food at a time of increased energy use from increased vocal activity (Oberweger and Goller 2001) and potential stress responses. Reduced self-maintenance behaviors, such as preening, may increase damage inflicted by ectoparasites (Clayton et al. 2010). However, birds may have compensated by increasing foraging and self-maintenance behaviors after we concluded observations. As such, brief changes in behavior (15-30 min) may not have a significant impact on survival or subsequent fitness, unless birds were already under duress. Longer post-treatment observation periods are needed to determine how long the treatment altered the birds' behavior and if birds eventually compensate by increasing foraging or self-maintenance behaviors. Birds also would need to be tracked to determine if survival or fitness was compromised in comparison to untreated birds"

http://www.seafwa.org/Documents%20and%20Settings/46/Site%20Documents/2018%20Journal/J5_19ManessandJohnson136-143.pdf - Johnson and Maness, 2018, "Response of Wintering Birds to Simulated Birder Playback and Pishing" in Journal of the Southeast Association of Fish and Wildlife Agencies


"The repeated playback experiments suggest that Plain-tailed Wrens may habituate to repeated short bouts of birdwatchers' playback after just 12 days of playback. This finding suggests that repeated playback may not have stronger effects on wren vocal behavior than single bout playback. It is possible that repeated short bouts of birdwatchers' playback could lead to birds treating playback as normal neighbors, as was apparently the case in Ward and Schlossberg's [19] long-term experiments. The wren nest building that we observed near the playback speaker supports this possibility. Habituation could explain why particular bird pairs that are repeatedly targeted by birdwatchers with playback stop responding and seem to "disappear" [45]. Considering the above, irregular playback could potentially have a greater impact on bird behavior if individuals do not encounter playback often enough to habituate, and respond strongly in each instance of playback. On the other hand, if habituated birds show less pronounced responses, they might be less effective at defending their territories from true rivals [46]. These alternative hypotheses require further investigation.
Our findings are from a limited sample of 12 groups of antpittas and 24 groups of wrens. Furthermore, playback impacts may vary depending on taxonomic group, song complexity, social behavior, and time of year (e.g. [12]), so additional studies in other taxa are needed to establish the generality of our findings. Although our data show that bird behavior changes in response to playback, we did not measure the effects of playback on components of fitness such as survival or reproductive success.
Our results indicate that birdwatchers' playback affects the vocal behavior of two species of Neotropical songbirds. This result suggests that playback could negatively affect species if they become stressed, expend energy, or take time away from other activities to respond to playback. By contrast, the habituation results we present suggest that frequent birdwatchers' playback may have minimal impacts on wren behavior."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797570/ - Harris and Haskell, 2013, "Simulated Birdwatchers' Playback Affects the Behavior of Two Tropical Birds" in PLoS One



"There were no significant differences in behaviour during the pre-playback phase between these two groups of males when the speaker, dummy male, and observers were within the territory of a target individual but the song playback had not yet begun. This suggests that both naive and experienced birds do not treat a human presence in their territory as a threat in itself, at least during the pre-playback phase. We also observed no significant differences in the number of flights and latency to the first flight or vocal response during the playback phase (3 min, during which a song of a foreign male was played back from the speaker). These two measures of a bird's response-number of flights and latency to response-are often used to describe birds' behaviour during playback experiments (e.g. Skierczyński et al. 2007; Brumm and Ritschard 2011), and here, these measures were independent of the previous experience of tested males. It seems that, after an acoustic intrusion, the territory holders tried to locate the intruder as fast as possible, regardless of any previous experience of lure by playback and capture by humans. However, this pattern seems to be species specific, since in the Willow Warbler, capture-experienced males increased latency to response to playback compared to naive males (Linhart et al. 2012)."

https://link.springer.com/article/10.1007/s10336-019-01647-w - Budka et al., 2019, "Experienced Males Modify Their Behavior During Playback: The Case of the Chaffinch" in Journal of Ornithology



The sense I get from skimming these articles is that the responses of birds to playbacks of alarm calls and songs varies not only be species, but within species by gender, age, and experience with humans. Some effects of playback sounds are not harmful, while others are harmful, and it may be difficult to tell which is likely to be which in advance. That's not to say playback sounds should never be used, but that it might be easy to overdo it and cause unwanted harm.