An app can receive a notification when a screenshot has been taken, so it could theoretically edit the last image saved to Photos.

https://developer.apple.com/forums/thread/93362

However, I'm not really sure that would work, since I don't think that would be able to bypass iOS prompting you to give that app access to your photo library.

There's a third-party "ScreenShieldKit" which claims to be able to do this:

https://screenshieldkit.com

So, apparently it's technically possible to block this, but AFAIK, Apple doesn't provide an equivalent to Android's FLAG_SECURE ("treat the content of the window as secure, preventing it from appearing in screenshots or from being viewed on non-secure displays").

DRM-protected video can't be recorded (or screenshotted) in iOS, but as another comment noted, that seems to be a video-specific thing.

Nah, the DRM on iPhones is much stronger than screenshot protection. When you’re watching DRM protected media you can still take screenshots but the part of the screen that has the content will be blacked out. Basically all forms of reading pixels from DRM windows just return nothing.

It works different, you can always screen record but apps can detect it and stop playing content while the screen is recording.