mobs and players dont get moved by lava unless they trying moving in it. If you move in it then you slowly get moved along by it.
example: https://youtu.be/UDAcVYaYHKs?t=739
MC-187853
Water / Lava doesn't move entities unless they move first
Resolved
Fixed
5
I experiences this myself a few minutes ago, but only for players and in water - if you can show that it affects all mobs, please provide a video showcasing it, or exact reproduction steps.