You guys have apparently partnered with Capitol One.
There's a popup - ignoring the irony of ignoring your very own popup blocker - that pops up frequently to offer some unwanted and unsolicited discount.
I click the never show again and it absolutely ignores that as well. You can't uninstall it because it doesn't "exist" as a extension.
C'mon folks! WTH is that about disrespecting your users? There are other browsers that don't insult us like that.

I've been using Opera and Opera GX for years now.
It seems like recent changes are being made that affect compatibility with certain web features.
Two things of note:
1 - websites not rendering properly like it suddenly "forgot" HTML and CSS.
2 - login dialogs not functioning - one I can specifically note is American Express. It just sits there and does nothing. Who knows what's going on because there's no error message.
This using Proton Pass to enter the user name and password. Works fine on Edge, Firefox and Chrome.

@stahl1990 Thanks that exactly fixed it lending credence to the opinion it's Opera trying to ask to install if it isn't.
Opera is getting way too many affiliates and trying to shove them down our throats IMHO.