see also the post " Metadata loading suddenly very slow"
I have the same problems with firefox on ubuntu 22.04. Very often another problem appears for me (only in firefox). The dropdown (dashboard, edit observation, …) on the top right of the dashboard ignores any input. No reaction in network, console, etc. of developer tools, any selection is simply ignored. Restart of the page in a new tab does not help. I have to restart the browser in this case