Further to my previous comments, I'm afraid, after many years as an Opera lover, I've now moved over to Vivaldi. Endlessly customisable and, LOL, made it look like the older Opera in Dark mode. Plus it has Side Notes built in and didn't have to find an Extension.
Repeating myself, the View 'Extensions Panel' (Not to be confused with the 'Side Panel'), is a total mismatch to the rest of the theme, Windows or Mac and looks unfinished.
Should Opera go back to the older theme prior to v60, I'll look at returning.
if your on windows another one you can look at is the cent browser. it truly is as feature rich as vivaldi. if i were still running windows i'd have it as by backup browser instead of chrome, yes that means in linux opera is last after vivaldi vivaldi-snapshot chrome.