update
I found this thread https://forum.corona-renderer.com/Animation in render farm flickering#msg193718 that says about corona physiclal material causing it. Don’t know if its the materil itself or the glass preset.
checked mine, changed glass to legacy material and problem solved.
I can send you the scene if it helps tracing the bug.
Please also note that the 4K Cache is an experimental GI solver. Switching to UHD Cache and enabling the “Animation” preset should prevent any flickering.
Bu as Avi suggested - please start a new support ticket and the team will investigate.