@poolchick3 To me, it’s not anything that would stick out I don’t think, but because you pointed it out, I do think your for forearms are a little small in comparison to your upper arm.
I, however, don’t think you’ve reached any type of ceiling for arm gains. What workouts you do and how you do them play a big role along with diet. How much time are you contracting your muscles during each rep and how many reps total do you do? Are you getting the right amount of protein and calories to see true gains? How often are you working out and are you recovering properly? You don’t have to answer these in the thread but I think answering them yourself and researching about muscle gain if you haven’t already, it would help a lot.
Also, I know you didn’t ask for workout suggestions, but rock climbing is a really good way to build forearm strength and size(bouldering and top rope). If you have a gym near you, give it a try if you’re interested and you may find a new hobby along with a great workout. Climbing was the only form of strength training I did for a year or so during covid and my arms grew to around 14 in. Not massive but very big in comparison to the rest of my arm. I was 17 at the time, but I still think it’d be worth trying.