When a creeper with a potion effect explodes, the resulting area_effect_cloud spawns pink particles -previously black from 24w11a to 24w12a (MC-269427) - instead of using the potion effect's tint. Likely due to recent changes in potion data.
Steps to reproduce:
Spawn a creeper.
Splash it with a potion.
Blow it up.
Everything is pink.
Can confirm. This will likely be assigned an "Important" mojang priority.