As is shown in the picture, the full content of notification is not displayed. I tried left-clicking it, and it disappeared, right-clicking it but nothing happened.
How can I see the full content of a notification if it’s too long for the top bar popup to contain?
I were looking for the same a few months ago, and couldn’t find any other way than using the Notifications To File extension, or dbus-monitor (dbus-monitor "interface='org.freedesktop.Notifications'")
I might be wrong, but other than mousing over the popup notification itself as it happens (or using Panel OSD to always expand notification) I don’t think there is a easier way in Gnome at the moment.
I am afraid so. After googling around, I found out that this notification behavior was reported to be a bug in bugzilla back in 2017! And after gnome moved from bugzilla to gitlab, there were also several related issues (and they are open). Sadly there seems to be no straightforward fix to this problem, for now.