Looks like my apartment portal for next year lets me pay rent with a credit card for a flat convenience fee of $3.41. If it matters, it uses RealPage, which is owned by Wells Fargo. I've heard this fee is generally percentage based (~3%) and thus makes it generally borderline or not worth it when it comes to using a credit card so you get rewards points.

Is there a catch, or did I really just luck out here? Seems like this flat fee makes it an objectively good decision to use it even just for rewards, let alone hitting spending thresholds for signup bonuses. I'm at a point where my organic spending isn't generally enough to hit signup bonuses on a lot of the most lucrative cards out there, so if this was possible it would really be a game changer for me.