I've attached a resource pack that retextures all particles to the unused angry villager face. Testing with this pack, it functions perfectly fine in a non-education world, but does not work when education features are enabled.
This happens in Java on servers too-- I wasn't sure if a separate bug report for that exists already so I just decided to comment here
Oh well, probably is. The odd thing was that it was significantly more lag when ticks were frozen, but yeah, wouldn't put it past it my computer to be the problem.
Just tested, resource pack works perfectly fine and retextures particles in a non-edu world, but the same resource pack does not retexture particles in an education world.
Oh! Just realized, MCPE-151773 looks like it might be the same thing I had. The world I was testing in did have Education features enabled, and I didn't think to test on another world.
this is intended behavior actually! you've got the villager trade rebalance experiment enabled-- this means villagers only offer a certain few enchants based on the biome they're in