It doesn't happen often but sometimes if I am in a cave and walk next to lava, not on it but on the block next to it, I will get the bubble animation over my health bar like if I was swimming and a split second later it would disappear but I would then be on fire.
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No, I don't have RTX and it also happens with water though it is not as important because I don't take damage from it. I didn't mean to choose RTX beta either lol. Sorry for that,

Duplicate of MCPE-65094.
See the second video in the playlist on the linked ticket.
Does this only happen in the RTX beta, or is it an issue in the Bedrock game generally?