Strange artifacts after Light Bake

Hello Friends,

For my first post i sadly come to you with an Issue.

I recently finished working on my environment project for my bachelors and added some extra models and tweaked some lightmaps when suddenly some strange artifacts in form of small squares in a diagonal line started appearing in 2 places. (Nothing changed from the normal workflow.)

I attached two pictures of the areas where the problem appeared.

I have tried everything i could think of from redoing lightmaps to remapping IDs on the meshes, using different lighting settings etc. and no results.
I really hope somebody can help me, so that i can finally get that thing up on Artstation :stuck_out_tongue: