For 1.20.5-pre2 to 1.20.5, in seed 8367416979447710802 there are missing blocks at:
-1089 -19 -416
-1082 -22 -425
-1082 -22 -422
-1445 21 -354
-1452 22 -365
-1456 23 -362
-2552 -9 -218
-2606 -39 -258
This seems to have been fixed in 1.21.0.22
In 1.20.5-pre-1, the floating block in eruption was patched, but not the missing block
Found this in 1.20.5-pre-1:
Coordinates: 8212 -4 105289
Seed: -2669732893306160261
I haven't been able to reproduce this since 1.21.0.20, while I could previously do it semi-consistently, so it might be patched, or just rarer.
There are no full rooms missing, just a few random blocks missing, and as this happens in almost every trial chamber with the new rooms, so I don't think it's necessary to specify the seed/coordinates (I also think I deleted the world from the screenshots so I don't know what the seed is.) For example, on the seed -9119114652075301261, there are missing/random blocks at 22 -2 830, 15 -1 819, 4 -1 826, 11 -1 837, 53 -16 820, 14 -18 826, 14 0 816, 15 -1 819, 25 0 822, 22 -1 830, -40 -8 811.
In 1.21.0.20, a Trial Chambers no longer generates at this location, and I haven't been able to find another instance of this happening, so it might be fixed, or it might just be very rare.
I managed to reproduce this while checking whether MCPE-179882 was still in 1.20.80.24, (last week i got it doing the exact same thing) but when i tried doing the same thing again it failed
An entire quadrant (as shown in the second screenshot) is missing. (by quadrant, I mean what is placed on Java Edition with /place template minecraft:trial_chambers/chamber/slanted/quadrant_1 through quadrant_4)
When the bug was active I tested creating a new world with the only changed setting being multiplayer off, and it still happened
I have no idea how to reproduce this, sorry. Also, for some stupid reason I deleted the affected worlds, although considering it fixed on restart I don't think they would be very useful
I tested this, it also happens in 1.20.80.22
This also happened on Bedrock 1.20.80.23
This also happens on Bedrock but I can't be bothered to spend another half an hour finding all the different places this happens
I don't know if this is relevant, but it's really easy to fix. Changing the Ore UI variable "DEFAULT_RESPAWN_RADIUS" from 5 to 10 fixes the problem
This was fixed in 1.21.50.26 as a part of MCPE-180725