Modpack
PlayerRevive_FORGE_v2.0.14_mc1.19.2.jar

My character starts swimming instead of lying still and waiting for respawn. The character can move around.

Actually you are supposed to move around. That is intentional. It uses the same animation when a player is pushed to the ground. I guess I can close this issue. You can use /cmdconfig and increase the slowness effect to stop the player from moving around. Sorry for responding that late.

Okay, it just seemed like a bug rather than a planned feature.