@leocg
Hi, sorry for the late reply.
From what I read from multiple forums, it only says that I have to manually export from Opera and then import to the other browsers, but none of them gives a reason why it is so when other browsers usually work.
I find it a hassle to have to do it manually, and I apologise if my post was a little "aggressive", as I was pretty annoyed and angry at both the bugs and this import problem at that time.

I find that Opera, whether it's a bug or doesn't want me to switch browsers, somehow isn't an option when I go to the "Import from Another Browser" window in about every browser that I try (namely, Firefox, Edge, Chrome and Brave). I'm thinking of switching browsers (don't hate me for disliking the many bugs I come across in Opera), but this problem has been bugging me for quite a while. I'm aware that I can export bookmarks and passwords through other means. Still, I find it too convenient that other browsers allow me to import data from all my other browsers, including ones I had already deleted a long time ago, yet, somehow Opera isn't showing up in any of them. It'd be much appreciated if someone could help me fix or at least provide an explanation for this.

One weird bug I haven't seen being reported before is that Opera sometimes exits fullscreen when I open a new window. My current fullscreen window is unaffected; only the new window is not fullscreen. The thing I find weird about it is that it seems to be "randomised" in the sense that at some periods, it opens windows in fullscreen normally, but at other times it exits full screen. Another weird thing I found is that while the bug is "active", I can try exiting fullscreen manually then simultaneously opening a new window with Command+Shift+N and changing my current screen to fullscreen, which opens a fullscreen window. However, when I open a window after that, it still exits fullscreen. Does anyone else experience this problem?