So many people say to isolate google play services in another profile, but I have not seen anything quantifying the amount of attack surface reduction or what benefit this gives in terms of anonymity or security. Google play services includes Firebase Cloud Messaging (FCM) which is what enables most apps to give timely notifications. There are alternatives like ntfy, but they require some understanding of how to set them up, and tinkering.
Finally, multiple profiles is useful for the most security conscious but for the typical user I do not believe its very useful. One thing I noticed is notifications are not consisently reliable, so setting up a “Facebook” profile does isolate you from the app but then you may miss notifications. You also have to type your password for every profile switch.
The ultimate in privacy for YouTube is Invidious https://invidious.io/, which fully proxies your videos from YouTube through an Invidious server. Every once in a while YouTube will get the upper hand and figure out how to fingerprint and block the servers, but so far the community has always figured out how to circumvent it. One advantage is that you can feasibly use a VPN with Invidious; without it, you have to keep hopping from VPN server to VPN server until you find one YouTube hasn’t already blocked, especially on a large public VPN like ProtonVPN. This applies to NewPipe as well, since NewPipe still tries to talk to YouTube directly as far as I understand. On Android I use Clipious as the app to access the Invidious servers.