Firefox Badly Broken By Latest Forced Update! Please Help!

[DinoNerd]

I'm running Kubuntu 25.10 I'm using its default firefox, which comes as a snap.

Yesterday I had yet another forced upgrade of firefox.

The first problem I noticed was that it no longer seems to have "duplicate tab" functionality.

I also can no longer find the firefox version number from within firefox, which I believed did work in its prior version.

Snap reports it to be version 148.0-1

I'm not sure what else has been changed, either by Mozilla or by the packagers of the snap. Presumably I'll find out, gradually, as things I do every day no longer work.

I don't know whether this aggravation comes from Mozilla, whoever builds the snap, or Kubuntu. I only care about that to the extent that this information might be useful in repairing the breakage and preventing it from happening again.

Any suggestions? For:
(a) getting "duplicate tab" back, as a menu item or button.
(b) getting "about firefox" back, in some form that doesn't involve typing a coded pseudo-URL every time I want that info?

*If* it's possible to restore firefox' previous functionality in the version I currently have, the simple thing to do is to do so, then freeze the snap at its current version, so this never happens to me again.

(c) Also, is it possible/convenient to roll back a snap to a prior version? I know I can pin them so they'll never self-update again, and kept a link to the instructions somewhere. But can I go backwards, and will going backwards restore my prior configuration, assuming this bad update changed that?

Worst case, I guess I'll delete the firefox snap, then download downrev versions of firefox from other sources, until I get one I know how to use.

But probably this is a change to default configurations, that also force-updates users to the new defaults, or force updates them if they'd been happy with the old defaults, and so made no changes of their own. So it's *probably* repairable without a rollback.

[DinoNerd]

On the good side, I can now disable all of Mozilla's AI features with a single switch, and without digging through hidden settings in about:config

Too bad I can't find a setting for enabling "duplicate tab" in that heap.

[DinoNerd]

I give up. The menu item is now present. Maybe I was browsing-while-half-asleep, and maybe there's something really subtle wrong.

[die.boer]

which comes as a snap.

therein lies your problem
if it was me i'd remove the snap and install the .deb version

sudo snap remove firefox

sudo add-apt-repository ppa:mozillateam/ppa

echo '
Package: *
Pin: release o=LP-PPA-mozillateam
Pin-Priority: 501
' | sudo tee /etc/apt/preferences.d/mozilla-firefox

sudo apt update

sudo apt install firefox

[claydoh]

Works fine on my 25.10 setup using Snap. Which means nothing really.

therein lies your problem
if it was me i'd remove the snap and install the .deb version

Not everything is caused by Snap. This is more likely (imo) something else, and something that can happen in a 'native' package, as it is more likely something in the specific config files rather than the application itself.

Too bad I can't find a setting for enabling "duplicate tab" in that heap.

You might test a clean profile to see if it is something in your configs, or maybe an extension, theme, or something. A corrupted file. Anything that modifies the look can do odd things like this. Including extensions, or combinations of them.

Firefox three-bar-menu >> Settings >> Profiles. You can switch between them and manage them from either the three-bar or by clicking on your account icon.

Of course, swapping to the deb version will start you out with a clean profile as well.

[jlittle]

The update to 148.0 caused problems on my media tiny PC. This was a nuisance because I don't normally have an accessible mouse or keyboard for that PC, controlling it only with KDE connect or ssh. Eventually kwin died, and I had to reboot the box. In future when I get the notification to restart firefox because there's a new snap a reboot might be the quickest approach.

Note that snap list reports "148.0-1" but firefox itself (firefox --version) says "148.0" and the firefox releases page says "148.0.0".

I note also that firefox 148.0 was released several days before it arrived as a snap. I've tried to keep the media PC as vanilla Kubuntu as possible but if I continue to have trouble I'll try a non-snap firefox. (I run the Mozilla download version on my desktop.)

[claydoh]

snap list reports "148.0-1" but firefox itself (firefox --version) says "148.0"

The -1 is a snap-specific build or package number, much like it is with deb files, such as kernel 6.17.0-14 being the 14th patched build of the 6.17.0 kernel version.
It is one of the small number of things I remember about versioning/packaging from when I used to run my PPA back in The Day.