Update your firefox now and the issue is gone.
It was basically the whole reason for the update.
Google changed their code to create a bunch of objects over time, and those objects didn't get cleaned up. It was just a standard memory leak issue.
Except it heavily impacted users who kept a youtube tab open or pinned.
The bug was reported and a fix released in a little under 2 weeks.
Update your firefox now and the issue is gone.
It was basically the whole reason for the update.
Google changed their code to create a bunch of objects over time, and those objects didn't get cleaned up. It was just a standard memory leak issue.
Except it heavily impacted users who kept a youtube tab open or pinned.
The bug was reported and a fix released in a little under 2 weeks.