188.8.131.52 won't zoom in or out
Middle scroll won't zoom in or out of web pages either. Tried other browsers (Firefox/Opera) to see if issue was same but only on Vivaldi.
This is a known bug. For now ctrl + should zoom in and ctrl - should zoom out. If not, you can set the shortcut in Vivaldi's settings.
BTW, no problem to set Ctrl+- but not sure how to set Ctrl++ (Ctrl+Shift+ doesn't do it).