I have a juvenile severe macaw with red on the belly. I have seen no other images of a severe with these colors on their bellies. Illiger's macaws have red bellies. Could this parrot be a hybrid? I am trying to upload a photo with no success. I am new to the forum. (See profile pic)
It is possible the chick is a hybrid, however if that's the only identifying feature, I'm going to say "probably not". Generally, there would be more indications of such a hybrid (I have yet to come across one of those hybrids), although thinking about the severe x RFM hybrids... well, they look like severe macaws on steriods! Well, they do have some RFM features too, but they take after the severes a lot, from what I've seen of the youngsters.
Anyway, since this is a chick, the red coloration could potentially be *normal* for the chick! Possibly even normal for the genetic line! And in time, the red coloration will molt out. This extra red coloration, sometimes called a "red diaper". You may not be able to know for sure unless
a) you are able to get in contact with the breeder or
b) wait to see if the coloration remains or molts out. If you didn't purchase directly from a breeder, you can always try asking from whoever you purchased your severe from if the chicks they receive in have this extra coloration or not. If they have been selling severe chicks from one breeder for a while now, they may be able to give you more information without having to contact the breeder.