The bug
Desert villages generate cactus blocks as part of the decoration. However, the placement rules of cactus blocks are not considered:
They are placed directly next to other blocks, which is normally not possible
They are placed on blocks other than sand (e.g. sandstone)
How to reproduce
Last tested for 20w51a
Seed
2497334744588602023
Coordinates
/execute in minecraft:overworld run tp @s 90783.40 65.01 -878.80 527.85 30.30
Linked issues
Attachments
Comments

Actually a duplicate of MC-136967
Can confirm. Further examples include: