I'm curious as to what you think an "age gap" counts as?
It's kind of rare to see a 10 year gap besides it is the uke who's older— yeah quiet strange
I can see you're new at this. There are tons of older uke out there. Take a classic example like kisa shouta from sekaiichi hatsukoi (altho he does look younger than Yukina), or the father from Not Equal (more than 20 year age gap).
As the other comment stated, age gaps with 10+ years where the uke is older is quite common. It's basically a trope b/c typical semes are the older, mature ones so it's pretty refreshing to see the uke as the more mature one. I personally consider anything less than 8/9 years not actually an age gap (depending on both of their ages). You should check out Naono Bohra's work if you wanna see more.
I'm a sucker for age gap just didn't expect the uke to be more older than the seme but good thing I never cringed to this