Is there a way around it? I have a website where you can buy a subscription through Stripe. Can I just redirect to this page from the Android app so they could pay through the web and that would automatically enable their subscription on the app as well?
https://digital-markets-act.ec.europa.eu/index_en
Notably you can check out their list of gatekeeper services
It's bad for the developer, sure, but what exactly is "insane" or "illegal" about it? They have created a product marketplace, and they let you sell there, and you must abide by their rules.
If you want to sell on Gumroad or similar services you also need to use their payment processor of choice, and give them a cut. If you want to sell on Ebay, you also need to use their payment processors of choice (and originally, iirc, you only had the option to use PayPal) and give them a cut.
And of course check the rules for selling your console game. They are 10x more restrive, and have been since forever. Not only you have to use the console markers marketplace, billing system, and pay a cut, for many wont even be able to do that, unless they accept your game.
The thing is, you don't "have" to sell in Play Market - even if it was the only marketplace for Android, it would still not be some basic necessity of life that you sell apps for Android. You could always find another trade, or sell PC software, or whatever. In other words, a marketplace for a mobile OS is not exactly a public utility.
(Full disclosure: I moved my apps off the Apple App Store/Google Play Store earlier this year. I wasn't seeing any value with distributing on them. After leaving, I've had better interactions with my users and almost all of the folks who discover my apps end up upgrading to the paid version. While my installs are lower, my conversion rate has never been higher.)
I don't see why it should be illegal to have fees and terms of use on your platform. Don't like it? Don't use the platform. You're not entitled to others' work.
Take Google or Apple Photos, for example. Due to this 30% cut, they always have an unfair advantage when it comes to pricing.
In the case of Apple Services, we don't know if, under the hood, they are using undocumented APIs or whitelisting internal apps to provide a better experience when it comes to background work. (Context: Apple claims that the iPhone performs backups and a bunch of other tasks during the night while the phone is charging. Personally, I haven't seen any app perform these long-running backups as smoothly as their in-house apps.)
This is not true? Huawei uses android but is banned from the US so Google can't take their money. Guess what... you don't need Google Play to distribute apps.
In most cases they allow users also to purchase subscriptions outside their app store, but you can't link directly to those purchases from within the app.
There are plenty of alternatives to the play store. They just don’t get the same amount of eyeballs or require slightly more technical users.
Raising prices usually feels happier than reducing costs and half the customers at twice the price will probably reduce support costs as a side effect.
Good luck.