I had one tab in Nightly that was showing either a solid color (black after the screen locked and I unlocked), or whatever was visible before I switch to the tab. I.e.:

• Go to a tab with mozilla.org
• Go to borked fortune.com tab
• screen shows fortune.com at the bottom, but shows content from mozilla.org
• mozilla.org content is scrollable
  Any tab I switch to would have it's content visible in the fortune.com tab if I switch directly to it.
  Doing a pull-down on fortune.com causes a spinning arrow (reload indicator) to appear, but it spins forever. Switching tabs didn't make it go away (though lock seemed to).
  Killing an restarting Nightly caused fortune.com to load normally.

I have a screen recording, and logs. I'll attach the recording, and can provide the logs to anyone investigating (not sure what PII is in there).

Too large to attach. https://photos.app.goo.gl/iRQbbeSoXSo5cqxL9

The severity field is not set for this bug.
:botond, could you have a look please?

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This does not seem APZ-related to me (if there's something I'm overlooking that suggests a connection, please let me know).

Not sure what the best component to track this is, but GeckoView is probably a good starting point.

The severity field is not set for this bug.
:owlish, could you have a look please?

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Hey Kaya, does this bug ring a bell? I think we have had more than one of these, it would be nice to have them connected.

This bug rings a bell to a similar situation when I was stress-testing the app under my controlled environment. As it was an artificial environment I did not create a ticket back then, but it is good that this happens in the real world as well.
I am not quite sure whether the device had limited resources (memory/cpu/battery) when this bug was happening (the description does not exactly sound like that). But for now I am linking this to the Tab Reloading meta ticket.