Prior to 1.20.2 introducing the always_kills_armor_stands tag, shulker bullets popped harmlessly on armor stands, and this mechanic was used in some popular shulker farms to destroy stray bullets or stop them from hitting shulkers when they shouldn't. Check this timestamped vid for a ~1 minute explanation.

Unfortunately, the change went unnoticed by farm designers until just before 1.20.2 released due to it being glossed over in the patch notes, so there wasn't really time to request a reversion. We also assumed a report would just be closed as WAI, but when the topic came up in slicedlime's stream a few days ago, he encouraged me to file one.

Ultimately it's nothing like the end of shulker farming if this is not reverted, but it was IMO a nice mechanic that worked very well for this niche use case, and the change broke some cool farms.