Firstly, why are you using Google? Secondly, you must be doing something else wrong because I have never seen that outside of NSFW stuff. The only time I go to reddit is on mobile via the browser when I'm searching for something, and I'm not logged into an account.
That’s great that it doesn’t happen for you. For me, any time I end up on Reddit in a browser on iPhone, it gives the obnoxious “open in app or continue in browser” popup.
I use private mode in safari though, maybe it’s not saving a cookie or something.
I also get a button along with those to continue in my browser (on mobile). I just tap to continue on Firefox, and it works (at least on any subs that are not NSFW).