In the past few Bedrock Beta's (including the current beta 1.16.230.54 version), caves have not been generating properly above y=0. This is visible in the surface terrain generation, where in worlds not using the beta version caves are generating, but in the same seed generated on the beta there are no caves generating above y=0 whatsoever. Attached are images of one seed generated on both the beta and the regular version of Minecraft Bedrock, depicting the clear absence of the cave above y=0. Caves also don't generate in mountains, which I believe may also be part of this issue.