If I open a link in a new window the old window comes on top after about 5 seconds. Just started 2 weeks ago
Opening new window by right clicking, then selecting "open in a new window". Have used this method for ten years and never seen this before. Even if I have clicked on some part of the new page or scrolled on the new page, it still reverts to the previous page after 5 seconds. If I click on the new tab it goes to the new window and stays there.
Wšykne wótegrona (1)
Just a note to say that I've noticed this problem occasionally, but I haven't figured out a pattern to it. The 5 second delay you're seeing may be related to what is loading in the page, e.g., content from a slower server, and Firefox waiting to switch back until the page is fully loaded.
If you notice the problem with particular sites reasserting themselves, that might help identify the issue.