Well, what are you going to do about it? Let's start easy, and work our way to the tough stuff. Bear in mind that I'm on Android, so my knowledge of iOS options is limited.
The subscriptions feed page
Maybe you just want YouTube to actually show the channels you subscribed to, instead of hoping they'll pop up on the front page. It's right there: https://www.youtube.com/feed/subscriptions
Bookmark it, delete the main page from your browser history, get creative. This USED to be what the front page did, if you were signed in all the way back in 2008. It also used to hide videos you already watched.
Installing uBlock Origin into your browser
Firefox and most other browsers have a way to install add-ons for all manner of uses, and the uBlock Origin add-on will block YouTube ads without needing any more setup. The official page will even detect which browser you have, and send you on your way.
Using uBlock Origin on mobile
There's a version of Firefox for Android, and that supports uBlock Origin as well! It works just as nicely, and that includes blocking YouTube ads. Just head to the same page above to install it.
As for iOS, Firefox points the finger at Apple for not allowing WebExtensions on their platform. Meanwhile, those weirdos at Kagi have made a browser that works on iOS and apparently does let you install uBlock Origin. Lemme know if this is true.
Using someone else's Invidious instance
Lemme start by saying that Invidious is made by some real pricks. With that out of the way, an Invidious instance is basically someone else's computer showing you a website that does most of the things YouTube does. It'll fetch videos from YouTube, it'll stream those videos to you, it'll show you the comments section, playlists, only difference to you is that the page looks a bit more barren. You can even get fancy with it, set up an add-on in your browser like Redirector to replace "youtube" in links you clicked with an Invidious instance.
These can get...spotty. Videos that still exist on YouTube can disappear from Invidious for no apparent reason, search results can get wacky. Generally, the older an instance is, the better your experience, but that tends to mean that a select few instances get hammered. With that in mind, go check out an instance, see if you like it
Using alt-clients
Here's what I do, personally. Alternative clients have a way of giving you everything YouTube really does while not pushing unwanted changes all abrupt-like, and they tend to work better than Invidious.
FreeTube is an Electron front-end for YouTube. It'll block ads, fetch your subscriptions, and play your playlists. The setup you need is to follow a link in the app to YouTube's site, request a file that includes your list of subscriptions, and import that into FreeTube. It's a one-time thing, and if you need to transfer computers, you can always export your data from FreeTube itself. They recently added the ability to hide channels (you know, in case you never want to see MrBeast's inability to smize ever again), and there's a whole host of anti-distraction features. The config page has the hash for a Bitcoin wallet, which rubs me the wrong way, but as a tool it works real well.
NewPipe is an Android app. You can side-load a package from their website, or get it through F-Droid. Much the same as FreeTube, if you want your subscriptions, you'll need that same file, the app includes a link to where you can get it, and then import it into NewPipe. At that point, it's feature-comparable to the official YouTube app, unless you wanna shit up the comments section.
The only downside to these alt-clients, in my opinion, is if you pause a video for too long, they can't resume the video the whole way. FreeTube needs you to Ctrl+R, and NewPipe needs you to close the video and re-tap on it.
Using yt-dlp
If you've read this far, and you've used the command line, believe me, you don't need my help. You may have already used youtube-dl, and just didn't get the news that there's a fork with more options. Well, that's yt-dlp. It's on Github, it's fully documented. Go check it out.
Using a media PC
Got an old laptop with HDMI out just gathering dust? Maybe your nerd friend insisted on getting you a Raspberry Pi for your birthday? Put LibreELEC on there, and plug the laptop's HDMI into your TV. You're gonna have to learn how to boot into a USB drive, but soon as that's done, the installer will take care of the rest. Just make sure you back up whatever sentimental photos and whatnot you have on there before you install.
Once you have LibreELEC and Kodi installed, you can install the YouTube add-on, as well as the Invidious add-on. They both block ads! The YouTube add-on can even work with the NewPipe on your phone, so you can pick out videos on there to play on your TV!
There's USB remote controls available, as well as air mice out on eBay. I personally use one of those Logitech keyboard and touchpad deals, but that may be overkill for you.
There's options besides Kodi, too! I've heard good things about Stremio, which streams from torrents, and then there's also Plex and Jellyfin. Shop around, take your time, find what works for you.
Using your own server
You know, you can make your own Invidious! With Blackjack! and hookers! If you rent a cheap virtual server, you can install YunoHost on it, and it'll take care of A LOT of the headaches of getting Invidious going for you.
Wanna go further? Get PeerTube, and have that automatically fetch your favourite YouTube channels' videos for you! Believe me, giving the middle finger to Google's mishandling of YouTube is a never-ending rabbithole, you can always go deeper.