Have you tried looking to see what is using the power? It might be one app that needs reinstalling or something similarly simple, so I'd definitely try to identify the cause before doing anything more radical.
Otherwise it might be worth considering backing up everything and doing a factory reset. It's a hassle, but can sometimes help with things like this. The thing is that installing a new major OS version over an existing one isn't a clean process: there may be data or settings that aren't really compatible with the new version, and cause things to misbehave. It's not that common, which is why the manufacturers don't force everyone to reset (would not be popular!), but everyone's phone has a different set of stuff on it, which makes it hard to spot all such problems in testing, and occasionally these things do happen. So a reset is one of the standard things to try if you get strange behaviour after an OS update.
(It's also conceivable that this is normal for Android 10 on the Stylo 5, but only if LG did no testing whatsoever before releasing it).