@leocg yes, that's exactly right. Having that tab come up every time Opera launches is not a show stopper but it is annoying after a year or three. I'd seen the suggestion a long time ago but I thought it worth asking.
It's not part of the startup option "show current tabs" (a group of 4 including old Hotmail and tech related Gmail) but it's possible Opera somehow adds the speed dial by accident. I don't think it does if I use the option to fire up with last used tabs but I didn't want that because I'm often investigating a tech issue, and may have tabs I don't want the next time, when I close Opera.
Hope that makes sense. Most browsers, from Chrome and Firefox to Brave and Iridium, I use the "last used' option but not Opera. If you are on the East Coast as I am, stay safe in the next storm they say is rolling in 2 days from now.