Its interesting isshiki showed eyes like jigen either suggesting to me it's a dojutsu, jigen was talking or that's how his depowered dojutsu looks like having normal human black eyes suggesting the byakugan isnt the original eyes of the otsotsuki.
Maybe isshiki wasnt born with complete byakugan I think his dojutsu is a sharingan so maybe otsotsuki members with sharingans have black eyes.
Maybe isshiki wasnt born with complete byakugan I think his dojutsu is a sharingan so maybe otsotsuki members with sharingans have black eyes.