Usage of cache .sonar/cache with GitLab


We have performance issue with sonar check job in Gitlab-ci.

Usage of caching for .sonar/cache is the guilty.
Over time the cache only grows with the .jar of all versions : with time we have cache over Gb.

A check without cache : 2 minutes
A check with cache : 4 minutes downloading cache + 1 mn check + 4 mn uploading cache.

Your recommandation: GitLab CI | SonarCloud Docs


To fix your build for now, I suggest manually clearing the cache, using that documentation.
To help us investigate the root cause of the constantly growing cache, could you please list its content and post it, with the private elements redacted?
Do you have an estimate of the time it took to reach that very big size, are we talking about days, months, dozens, or thousands of builds?