HD Cache GI solver is deprecated - it can cause flickering, and will be removed in the future. We recommend switching to the new UHD cache and re-saving the scene.

This message will occur when you have Secondary GI Solver set to HD Cache. This is an old, deprecated solver, which provides worse quality output, especially in animations.


Solutions:

Switch Secondary GI Solver to the new UHD Cache.

See: Using UHD Cache