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 switched to Firefox last year when talks of chromium manifest V3 First started popping up. I had used Firefox many years ago when Chrome was first coming out. I was blown away at how well it worked compared to old Firefox, plus how easy they made it to switch. I even changed my phone browser and my desktop browser ties in with it seamlessly. Very happy with the switch and I wish I had switched earlier.
Now, I just wish I could use it at work. Not sure how I’m going to block ads on my work browser.
My work blocks all kinds random software, Firefox included. My workaround is using Brave browser and a service like NextDNS either as an app or as the DNS provider for my home network. It’s not perfect but it’s flexible enough.