After making a change to any card in lovelace and pressing save, HA pops to a different page.
I think this has been a problem for many versions.
While I’m at it when trying to change the order of entities in the editor this hasn’t worked for a long time ether.
These are not problems in ms Edge. But who wants to use Edge. not me.
I also see this behavior long time. I just got used to it. 
Good to know im not alone here :), was beginning to think my Firefox was fu, even do so when click Edit on the card, and then Cancel, very annoying and weird
There does not seem to be an issue open for this. You can create one here:
Might be an idea, thou still, atleast i thought, until now, that it was my Firefox, as i do have some “tweaks and add-ons”, that i haven’t “excluded”, well i actually haven’t done any “troubleshooting” , so no valid reasons to open a Topic or report anything
What version of FF are you using ? I’m on the ESR branch (91.8.0esr) and everything you described seems to work fine here.
im not surprised, i used ESR before on this laptop, but for some reason i installed “standard” after last time i had to reinstall windows, and it’s 99.0.1, just checked on another laptop with 97.0.0, same behavior
Anyway, as this laptop(my work/testing), and in specific Firefox, seems to “feel good” with a new install after few years, i guess i go back to ESR
I hope I did this correct.
This happens to me too once in a while.
Using standard FF, mostly the latest version with some add-ons.