When the Plex Media Server has an update, there are currently 2 options Dismiss or Download. I often find I then copy and paste the version number into google with the works Plex Update to see what the features are.
I think with every update, there should be a third option of Whats New which opens up a tab with the change log. This would allow for the ability to see what is new before deciding if you need to update or postpone. I typically will ensure I update timely for issues that impact (or may impact) me.
FYI, it is available now, just in a different location / manner.
In PMS Settings -> General, if an update is available there is a link to a “What’s New” instead of showing “Up to date.”.
You can subscribe to the Plex Media Server announcement thread. You’ll receive an e-mail when the thread is updated. To subscribe, scroll to the bottom of the thread and change status from Normal to Watching.
Early 2021 clean-up: implemented (clicking on the update notification will bring up a page that allows to download/install AND shows what’s new/fixed in this update)