In resource packs, a blockstate file may be formatted to begin with the following:

{ "variants": { "randomised": [ etc.

in order to randomise the choice of model used when rendering a block. However, in 1.20.2, blockstate files using this randomised variant functionality no longer work, despite the same files operating correctly in 1.20.1.

I believe this is a bug, as I could not find any reference to a change in format to randomised variant models in the changelogs, but correct me if I'm wrong.