After Unity upgrade it broke all prefabs

[kenorb]

After Unity upgrade from 2021.16f1 to 2021.18f1 (same for 2021.19f1) on Ubuntu, it broke all prefabs for the whole scene upon reimport causing most of meshes to disappear. It modified all meshes despite they weren't using LOD.

For example, for all subitems in prefab, it renamed the main subitem from "1-Default456" to "1-Default456_LOD0", then created 2 children with LOD1 and LOD2, this broke the whole scene (I've tested it couple of times, same thing happened).

It modified file.fbx.meta to:

 ModelImporter:
-  serializedVersion: 19301
+  serializedVersion: 21300
+    removeConstantScaleCurves: 0
   meshes:
-    lODScreenPercentages: []
+    lODScreenPercentages:
+    - 0.5
+    - 0.25
+    - 0.01

I had to restore from backup and get rid of the plugin. Let me know if you need a reproducible steps.