You can bookmark a whole window full of tabs all into a single bookmark folder. It’s called “bookmark all tabs” or something like that. Then later you can open all of them again into a new window using a single button again.

I know the average person isn’t tech savvy, but this loss is almost entirely on themself. If you have 7000 tabs open and it’s important to you that they stay saved, then it’s on you to simply ASK someone if keeping them open is an ok way to do it