There is a variation of betta called plakkat and the finnage is shorter. Google images with “plakkat betta” and you will see many examples. And young ling finned varieties take time to achieve full finnage

 

I just see a nice long finned HM

 

He's still a baby and, IMO, his fins are very nice.

We're so used to see Betta with exaggerated fins that we don't often recognize Betta with proper ones.

 

Looks beautiful , he's just a little one

192.168.100.1 192.168.1.1​

 

His fins are rather small for a long fin. But in my opinion, they're decent (not exaggerated).
Either way, he looks amazing