keyboard navigation broken

Can you give some more information about what your environment comprises? OS (+version), browser (+version), browser addons/plugins that might affect this kind of behaviour?

1. This behaviour is unintentional.
2. To my knowledge, we have not made any changes in recent past that could have caused this regression.
3. It Works On (4 of) My Machines (TM)

Happy to look into this, but need some information that could point me towards a particular avenue of investigation.

Firefox 115.9.1esr on Debian bullseye… but the fun thing is, I cannot reproduce it right now. How strange.

I *do* recall running into it multiple times already. The symptoms were that I could either scroll down with PgDn but a PgUp would bring me to the top, not just one screen page up, or (happened only once) that they wouldn’t at all work.

I’ll report back when I run into it the next time.

Oh wait, now it happened again.

I Ctrl-C’d the URL <https://bugs.launchpad.net/ubuntu/+source/xz-utils/+bug/2059417/> then I closed its tab, opened a fresh one, pressed Ctrl-V+Enter, then pressed PgDn twice as the page was loading, and now the PgUp and PgDn keys don’t do anything again.

Nothing in the F12 console.

Then I clicked on the word Changelog in the text “Changelog entries since current noble version 5.6.0-0.2:” and pressed PgDn, and it jumped to the beginning(!) of the page. Further presses of PgDn seem to make it scroll down one page at a time as normal, but a PgUp press then sent me back to the page top again.

I do have a few browser extensions installed, but probably less than many. I don’t know how I can figure out which ones are active on that page, though (I’m a console developer, not much of a GUI user); the extensions menu only shows Consent-o-matic. “Detect Cloudflare” is on but only shows an icon next to the URL bar, and “Dark background and light text” is on but disabled. “Regex search” shows in the menu as inactive because it needs permissions for the page/site. And finally, Editable QR generator is on but just adds a menu entry, too.

I am also not being able to reproduce the issue in any of my browsers.
I don't think there has been any recent changes that could have effected this either, as Clint also mentioned.

Just to be completely sure, could you try the same steps on another Launchpad page and on another website (not Launchpad)?

It seems to happen only for Launchpad bug pages, e.g. it does not happen on the answers page here, nor elsewhere.

Thank you for checking.

In that case, feel free to open a bug report with this info. From my quick look I couldn't find other people reporting the same bug, but if there are they will be able to mark it "this also affects me" which might also provide us with more information on what might be causing this for you.