Don't forget Ubuntu MATE 20.04 is End of Life, thus has been updated in a somewhat long time.
Ubuntu 20.04 LTS is also in its last days of standard support, with its five years already used up, and now into the additional month provided by Canonical
You're using an OS that is old and not receiving updates that newer software will get, so additional problems can often be experienced (when changes are made; maybe cyberghost have made updates your older OS isn't aware of).