:thinking: maybe this is the same/related to the issue I reported in #7148
Hello @GoTeamAnt, per "Improved Shader Pre-Caching behavior around game uninstallation." in the 2020-12-31 Steam client beta update, please opt into Steam's beta client and retest this issue.
The shader cache directory for rocket league seems to be gone. (no /home/xxx/.local/share/Steam/steamapps/shadercache/252950)
When I enabled background compiling* there was no indication that the rocket league shaders were compiled.
I did not install the beta client.
*I have it disabled usually
It's unclear from the last comment if that was a valid retest for the issue in the opening post. Closing pending feedback that this is still a current issue.
Shader background processing works OK. Just tested. @kisak-valve

Nothing extracted yet.
With background processing of vulkan shaders enabled, shaders for unistalled games are also compiled.
In the settings window I could see that rocket league shaders were compiled even though I had uninstalled the game when they dumped the linux version.
System: Archlinux