I also want to drop Grayjay in here. It supports YouTube and can also be used to view other platforms like Twitch, Odysee, PeerTube, etc. It uses plugins, so you can develop a plugin for the video platform you want to be able to use in Grayjay. Grayjay also has this Polycentric "decentralized" database so that you can comment and like the videos in those aforementioned platforms.

All I want is an ad-free YouTube app that lets me cast on Chromecast directly.

So far nothing worked properly. Any ideas? I'm using a Pixel 4A.

I've been using pipe-viewer (formerly/alternatively youtube-viewer) for years. It's an extremely minimal yet feature-rich and customizable perl youtube client, designed to be used without a google api key (If you want to use an account, use youtube-viewer instead). No other client I've tried comes close in my experience (I've tried Freetube (bloated), Minitube (buggy, feature incomplete, uses embedded player), Newpipe (restricted to android)).

Also works great on mobile, and can be used with a Gtk-perl client for people who want a graphical client. It can also be used with any native video player, like mpv or mplayer (and adding an unsupported player is trivial in the config).

Demo:

Using Tubular, which is a fork of newpipe with sponsorblock integration. It's a bit buggy but I like not having to skip every sponsor

youtube.com + firefox android/fennec + ublock origin + sponsorblock

Wait, revanced works again?

This was me when Invidious and Piped were being attacked by Youtube and Newpipe had a hiatus.

Tubular is a Newpipe fork with Sponsor Block integrated for anyone interested.

I'll also plug SmartTube, an Android TV app that has many of the more widely-used functions ReVanced has (blocks ads, supports SponsorBlock, etc.) among other things.

I'm having great time with FreeTube Cordova lately, you have to setup the UI initially, understanding its limit for mobile, but it works very well.

I would use Libretube, but it simply doesn't work on my phone. On PC I always use piped.

Libretube seems to almost never work for me no matter what instance i try.
Also worth adding Smarttube for AndroidTV

Tubular: A fork of NewPipe (Github) that implements SponsorBlock (Github) and ReturnYouTubeDislike (Github). https://github.com/polymorphicshade/Tubular?tab=readme-ov-file#a-fork-of-newpipe-github-that-implements-sponsorblock-github-and-returnyoutubedislike-github

Still in development but Lighttube seems interesting and uses its own backend.