The ability isn't broken at all. The JPIV needs camo to be highly effective because it's the least mobile TD in the entire game outside of the super heavies. Any nerf to the camo would need to come with either a buff to it's surviability or maneuverability.
Ok, let me put it this way.
Not long ago I uploaded replay.
On this replay, I attacked almost dead JPIV, on open field with 3 T34/76s.
Next to JP4 was KT.
My plan assumed that I will lose 1 or 2 T34 but I will kill vet 4 JP4.
Guess what.
I went behind JPIV, I was around 20 range from its ass but then it dissapear.
So my T34 automaticly switched to KT and before they could even aim and fire, JP showed up again, so I order them to attack JPIV again. Before they could fire, JP dissapeared again. Over and over.
Finally I lost 2 T34 and JP got away.
Open field, 3 T34 around and it dissapears in the middle of nowehwere in front of 3 tanks.
So, say again it's not broken.