I have Plex Version 184.108.40.20635 installed on Ubuntu and am being notified that "An update is available".
The "What's New" description indicates the current version is Version 220.127.116.1158
So I ran
sudo apt-get update followed by
sudo apt-get install --only-upgrade plexmediaserve
The response was as follows:
Reading package lists... Done
Building dependency tree
Reading state information... Done
plexmediaserver is already the newest version (18.104.22.16835-313f93718).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Has the updated version not been pushed to the repository yet?