Prior to 24w19a, projectiles with the 'power' tag could reliably be accelerated by the player using e.g. bubble columns or pistons. The replacement of 'power' with 'acceleration_power' introduced probably accidental but significant changes to how this acceleration works, and it's likely that setups built by players will no longer function (or worse, blow up surroundings) in 1.21 unless the difference is rectified. 

Attached is a 1.20.4 WDL with two example setups including signs indicating where projectiles end up in 24w18a and older versions as well as where they'll end up in 24w19a+. 

Steps to reproduce:

1. Download the attached world
2. Load it in 24w18a or earlier
3. Note where the projectiles land (marked by signs for both behaviors anyway)
4. Load the same world in 24w19a and later

Observed result:
The projectiles land in different places in 24w19a and above compared to 24w18a and earlier. 24w19a changes introduced additional weird behavior. One example is shown in the WDL, and two other examples are shown in the attached short clips provided by jjl21.

Expected result:
The projectiles land in the same place as they did in 24w18a and earlier and don't behave weirdly.