EDIT: Apologies. Updated with a link to what gorhill REALLY said:
Manifest v2 uBO will not be automatically replaced by Manifest v3 uBOL[ight]. uBOL is too different from uBO for it to silently replace uBO – you will have to explicitly make a choice as to which extension should replace uBO according to your own prerogatives.
Ultimately whether uBOL is an acceptable alternative to uBO is up to you, it’s not a choice that will be made for you.
Will development of uBO continue? Yes, there are other browsers which are not deprecating Manifest v2, e.g. Firefox.
I know, that some day I will have to switch to Firefox. But I’m putting it off as long as I can, as I don’t like that browser. I will have to instal a shit load of add-ons to get the customisability of Vivaldi, and I doubt k will get it all.
Use https://floorp.app/en
Do you even need uBO on vivaldi, though? A friend of mine recently had an issue of sites breaking, even with all addons disabled. As we found out, vivaldi already has a built-in adblocker, which uses pretty much the same lists as uBO. In the end it turned out to be one of the easylist’s borked rules…