I think I’ve explained quite well already, but again, many vendors, like Samsung, kill any background jobs before they have a chance to run. No matter what technology you use, it will get killed. The only thing that doesn’t get killed is an exact alarm that’s allowed to wake your phone from sleep. Everything else will get killed on Samsung. Including periodic alarms and including work manager, periodic or not.

I have no idea what the rest of your message is even talking about, I don’t have any WallpaperService, I don’t do any of what you mention, so I don’t quite understand why are you even talking about it.

In conclusion, further discussion on this topic is unnecessary because you seem to be rambling on and on about stuff that’s not at all related to why the battery optimization exception is needed. It’s not because of stock Android, but because of other vendor’s flavors of Android.