Why would a 50amp gfci circuit breaker get hot?
Warm is normal if fully loaded. My guess is that this CB is for
a hot tub which has a large heating element. HOT means something is
wrong. Probably loose contact between the buss of the panel and the
blades of the breaker; could also be internal failure. Turn off
power and pull the breaker out to inspect where it plugs in. Any
discoloration in the metal is a sign of failure.