It appears that at least on 3.36.5, when installing from extensions.gnome.org, it tries to install version 14 for 3.36 instead of the most recent version 15 for 3.36.4.
Upon manually installing version 15, it informs of an update available that will then downgrade back to version 14.
Okay, I can't seem to reproduce the downgrade attempt after a manual install. It still installs the wrong version from e.g.o for some reason, though. Changing the issue title.
It appears that at least on 3.36.5, when installing from extensions.gnome.org, it tries to install version 14 for 3.36 instead of the most recent version 15 for 3.36.4.
Upon manually installing version 15, it informs of an update available that will then downgrade back to version 14.