I use a few:
- Adguard (blocking ads).
- Vinegar (blocking YouTube ads and allows me to use iOS video player, with PiP, alongside other options like default video quality).
- SponsorBlock (Skip YouTube ads. Works great without Vinegar, and just okay alongside Vinegar).
- Baking Soda (like Vinegar, allows iOS default video player with other websites which are not YouTube related).
- Userscripts (allows loading scripts into Safari. I mainly use them to bypass some paywalled articles, and restore the YouTube dislikes counter).