Pretty sure mine was 1.17.34 before opening it to 1.17.40 today
This sounds like it might describe my problem. When I opened my Realms world after the 1.17.40 update I found that the chunks around my home base suddenly reloaded with weird groups of leaves and an eerie wall of water floating high above sea level that definitely weren't there last time I played pre-1.17.40.
[media]
Oh looks like my problem is the same as the open MCPE-144937 issue and the similar issues marked as duplicates of MCPE-144937