There are definitely more and less reliable 3rd party batteries.
If Canon is going to do this, I sure as hell want some explanation about why... I've never bought, to my knowledge, counterfeit batteries and that deception there would worry me. But that's a very different story that responsibly labelled and tested 3rd party batteries. The "scare" warnings that have existed in cameras about "unidentified" batteries have been mildly annoying, but the camera+battery still work, so no big deal. I don't really have a problem with that. But I find it hard to believe that the LP-E6P or R5II contain something so proprietary it's impossible to manufacture as a 3rd party.
Personally, while not ideal, I think they could lean into what Apple did with the "MFi" certification program. Maybe the problem is that it'd be hard to find a market for 3rd party sellers that could pay Canon a $5 license fee or something and still price their batteries accordingly... but I'd happily spend a little more for 3rd party "licensed" batteries over unlicensed ones if such existed.
Whereas, today, I seldom pay Canon's prices for batteries, DC couplers, chargers, etc. I supposed I'm in the YMMV camp and while I've definitely had less good 3rd party batteries (yeah, $15 for a LP-E6 was no good LOL!), I've not had a problem in 4 different bodies over 15 years, and now I've got an R3 with a 3rd party LP-E19 and it's going well, too. Even USB-C charging is working which is great, since the LC-E19 charger is a beast and I don't want to travel with it unless I have to.