I've been constantly frustrated in a similar way since when the address bar became "smart".
My only request is this: There should be a switch to turn all autocompletions into genuine "suggestions".
In the simplest scenario: You type some text and hit the return key . . .
Current behavior: An autocompletion replaces the text and the new text is sent to the browser.
Desired behavior: The typed-in text is sent to the browser as is unless you actively select one of the suggestions.
[Note that there may be a shortcut to select what you have just typed over autocompletions. While I'd like to hear about such a shortcut, it wouldn't be a solution to my problem, because on all other apps, autocompletions are just suggestions which are dismissed unless the user actively selects them. It's only Vivaldi (and Chrome?) that forces completions on the user. For this reason, my muscle memory makes me repeat this frustrating behavior described above.]
[Note that disabling autocompletions isn't a solution to my problem, because suggestions are very often useful.]
I searched the "Feature Request" forum, but haven't been able to locate the same request. Perhaps I should submit this in that forum.