Debian buster, R latest, RStudio latest.
R_LIBS_SITE env seems to be set but null when executing /etc/Renviron from RStudio server.
base/Rprofile keeps the null value. End-user end up with an empty R_LIBS_SITE.
I'll try to narrow down where the variable is set and compare to previous RStudio release, seems to be from RVersionsPosix.hpp. I'll come back here if I find something else.