As of the resolution of MC-240393, it is intended for jungles to not generate on plateaus. However, this does not happen consistently with different humidity levels, causing unnecessary microbiomes. As shown in the screenshots below using the seed -7458002248321719613 and going to the coordinates 9 129 119, jungles will still generate at humidity levels of 4 on a plateau, while jungles on non-plateau terrain have consistent generation between humidity levels of 3 and 4.
MC-265421
Jungle biomes can sometimes still generate on plateaus
Resolved
Invalid
2
(Unassigned)
Community Consensus
World generation
1.20.1, 1.20.2 Pre-Release 4, 1.20.2 Release Candidate 1, 1.20.2 Release Candidate 2, 1.20.4
Retrieved
I do not think that the resolution of MC-240393 means it is intended for jungles to not generate on plateaus. It just means that it is intended for forests to generate on plateaus.