2022, you say?
Well, one way is to carefully read through the update announcements from 2022 to current, and find every reference to a .pacnew file being provided via an update.
Naturally, that would be time-consuming, but effective nonetheless. This is an important step, as simply merging each .pacnew can potentially cause more complication; each should be handled carefully, case by case.
You can see the System Maintenance page in the Manjaro Wiki for a brief overview under the heading Pacnew and Pacsave files – a forum search will reveal more specific information on how to use the respective tools available.
I’m afraid if you’re looking for a quick fix, you won’t find one; each file should be merged or replaced dependent on the reason for the file existing in the first place.
In some cases, replacing a file might overwrite personal settings. In other cases, only specific (usually newer) content should be merged, and so on.
As @BG405 warned, these files should not be handled blindly.
Pamac should never be used with sudo; if elevated privileges are needed, it will prompt you to enter your password.
So, yes, if you made a habit of using sudo pamac ... it’s likely you’ve not done yourself any favours. 
Using pacman is almost always my preference. The only time I use pamac is to install an occasional flatpak or rebuild one of the few AUR packages I use.
Pacman isn’t difficult once you get used to it.
- Pacman Overview (Manjaro Wiki)
- Pacman (Arch Wiki)
And a quick reference guide can be found here:
- 11 Ways to Use Pacman on Manjaro Linux (ignore the last section where the author infers that Pamac is a frontend for
pacman– this simply isn’t true).
Handling the .pacnew files isn’t overly difficult, but I imagine it can seem daunting if you’re not confident with the concept.
As you already seem amenable to performing a reinstall, that is always an option. It might also give you the opportunity to invest more time in learning important maintenance tasks.
All the information you will probably need already exists as Tutorials from other members, or in the Manjaro Wiki.
So, all it takes, really, is to make a conscious choice between reading or playing a game for a few hours. 
Cheers.
Edit:- Typos.