When open extensions.gnome.org and open any extension, I can press button on/off. It switches but nothing happens, no message about installation pop up. Previously, a year ago, on other machines with 20.04, everything was fine.
P.S. I install gnome-extensions, chrome-gnome-extensions, gnome-tweaks. Tried chrome and firefox and install required extensions and them.
P.P.S. It turns out that extensions can be installed manually quite easy: https://itsfoss.com/gnome-shell-extensions/