From what I know, reddit is not entirely to blame on its own on this. Apple's policy only lets the first party app open certain domains, like YouTube (please correct me if I'm mistaken) and Twitter. Overall, a decent workaround is an app called Opener (link to follow) which lets you switch to specific apps from the share sheet. Apollo also has this feature for reddit links specifically.

However, I do agree that reddit's behavior beyond that is obnoxious.

Opener link: https://apps.apple.com/us/app/opener-open-links-in-apps/id98...