Reported here https://unity.slack.com/archives/C06TQ5M4J/p1612860769108400

How to reproduce:
1) Open a project.
2) Drag a new texture into the project.
3) Select the new texture in the inspector
4) A warning is printed: The GI Cache is using increasing amounts of space on your hard drive to support concurrent Editors generating lighting. To prevent failed bakes, close all other instances of the Unity Editor.

The warning is logged about 42 (:42:!) times in my editor. But, I’m never running several editors at the same time!

Wild guess: maybe the whole system is detecting that new “asset preview generation & search indexing asset database worker” process that is spawned in the background all the time, without user being aware of it, since 2021.1 or so?

Regression was introduced in https://ono.unity3d.com/unity/unity/pull-request/117241/_/lighting/bugfix/1266726