@jb510 Thank you for your hints.
@jamesosborne I followed your guide and installed the helper plugin. Could you please confirm if correctly? Firstly, I installed and configured helper on staging environment (directing site address to prod), but it didn’t seem to change anything. I still got a loop directing to the stage.
Should the helper plugin run on staging wordpress or production wordpress, or even both?
Meanwhile, I decided to delete GSK from the stage, which solved the problem until next staging rebuild.