Just made an account to report this in, given I haven't seen it mentioned anywhere else: Wide Guard and Quick Guard appear not to lose success rate with consecutive uses like they used to. I saw a Mantine use Wide Guard in Le Yeah four times in a row, and I just went and tested Quick Guard and got seven uses in a row. Sorry if this just hasn't been added to the original post or is wrong or something: I encourage people to test it out for themselves, since all you need is a pokemon with the relevant move and somewhere to get into a battle.
Additionally, the description now reads "The user protects itself and its allies from priority moves" for Quick Guard. No mention of a failure chance if used in succession.
EDIT: Just tested 15 Quick Guards in a row, zero failures. Will now check how it interacts with Protect. I'm guessing Wide Guard will be similar whatever happens, but I don't have anything on hand to test that with.
EDIT 2: A preliminary sample of five Protects followed by Quick Guards suggests Quick Guard after Protect also does not suffer from failure. However, I can confirm that Protect after Quick Guard is susceptible to failure, meaning it's likely Quick/Wide Guard still count as "protection" moves, but don't have the failure chance themselves.