Google's only providing the option, it's up to individual devs to enable it on their app. If the app developer has chosen to block sideloading, then they probably have a reason for going out of their way to do so. Whatever you find that reason to be should inform your decision whether or not to continue using their app.
Their reasons means nothing. It's my device. I shouldn't have to worry about an application installed on my device being policed because the developer got a hair up their ass about people downgrading.
Explain to me what would be the good reasons McDonald's has to block their app from running on a rooted device because it doesn't pass SafetyNet or whatever Google is calling it now
It's the same system, it's all part of play integrity. And that also applies to this bullshit, why does McDonald's care if I didn't install their app from the play store?
Oh I don't know if mcdonald's specifically does this, I've never used the app, I just used it as an example because that's what the guy above was talking about as well.
If I had to guess, I'd assume it's because there's a payment system in their app and they don't want people monkeying around with it and stealing food.
McDonald's was just an example, the point is most apps don't need to do that at all.
I do happen to know how payment systems like that work, and thankfully those are all cloud-based, the only thing the app does is start transactions and check with the server if they're paid. If they implemented it well, as I suspect a big corpo like McDonald's probably would, their own order screen also checks server-side if orders are paid. Not much you can do from the app side to mess with that.