Is there a way to prevent Safari from quitting if multiple tabs are open? A way for it to ask me like in some other browsers if I'm sure I want to quit
This thread is offering some solutions - although I'm not sure any of them have helped yet. I think Apple took it away permanently. Who knows.
https://forums.macrumors.com/threads/1215268/
This isn't a solution but it might save your day: when Safari reopens go to History and select Reopen All Windows from Last Session.