YouTube is absolutely unacceptable quality. The difference is clearly audible even on $5 earbuds. I feel sorry for your ears if you don't hear the difference, but the vast majority of those who care enough to download music will be able to tell the difference.

I personally pay for Deezer HiFi and save the FLACs locally. Friends mostly do the same with Tidal, but both work well for this purpose.

If you want to find FLACs without paying for a service you can check out rutracker. It has torrents for discographies from a lot of famous artists. Alternatively, you could find a stolen account for one of the previously mentioned services, but that goes too far for my morals because you're hurting a normal person with a hacked account.