I had the same problem, I think it was caused by the Huawei app store, since I disabled it youtube seems to stay deactivated.
It's not Huawei nor their app store...
I have a similar problem for the past couple of months or more but it's related to Chrome and Duo, they keep re-enabling themselves. To-date occurring on my P20 & Pro, Moto G7, and G8X ThinQ, not an issue on my Pixel 2 XL. And "Auto-update apps" on all devices is set to "Don't auto-update apps".
Over the course of time what I've noticed is "
Android System WebView" appears to be playing a role in this because every time it gets updated at some point so does Chrome and Duo. So I've tried not updating WebView and/or disabling. Nope does not work nor has the several updates WebView has gotten done any good.
The most frustration part, all three of these apps have a mind of their own updating at will and whenever even though I've requested don't auto-update apps. Read where others are having similar problems too and from my gathering, this is only related to Google's apps.
BTW... Factory reset my P20 Pro a week ago as a new device (no backup and first time in two years), nada same problem. Also tried multiple suggestions on all my devices and they too did nothing to fix issue. Not planning digging any deeper as shouldn't have too since all was fine for many moons prior, just hoping a fix comes along at some point to rid those of us affected of this annoyance.