SOLVED!!
Ubuntu 20.04 requires the R Studio version for Ubuntu 18+ and not the Version Ubuntu 22.
This issue was solved after I encountered the following error :
rstudio: error while loading shared libraries: libcrypto.so.3: cannot open shared object file: No such file or directory
It was simply a R Studio version compatibility problem, which is described here : Ubuntu20.04 needs other version of RStudio.