it is the same as mine MC-241239
did you update the world to 21w42a if so that is why don't know why it is that version that makes the world gen glitch out in old gen
if you go to/ make new chunks in 21w43a or new the new world gen will work but not for the chunks that are generated/updated to 21w42a
[Helper] pine1needle
Sorry I for get that I updated the world first to 21w42a or a older version of 1.18 then updated it to 21w43a and there was no new weld gen and if you updated the world agen to 1.18 pre-release 1 there is still bedrock at y level 0.
will add pictures to show what I mean
[Mojang] Moesh here is the link to where you can download my world https://drive.google.com/file/d/1Tuogted1RJjCOhP0j5GE6ODsZ77cr3Nl/view?usp=sharing