Alt tab is definitely not the only cause/trigger for this as it happens to me exiting portals and other dialogs in game as well.
Honestly I’m using alt-tab a lot more lately because of these threads (just being reminded) but I almost never used it and have had this problem frequently since at least early last year, which is when i finally realized what was happening.
Just a more recent threat I started on the topic - there are much older threads including one from … tagris I think … where I was like “it’s not that big of a deal” because it was happening infrequently in the beginning. It happens to me a lot more now.
Clicking the button usually stops it, but sometimes it seems like I have to click a couple times. Either way it just extends the damage if it’s a bad situation.