I had a female GSD and a male Aussie with umbilical hernias by 8 weeks old. Both were fixed at spay/neuter at 6 months no problems before or after. This was some time ago (12 + years) but in both cases, the vets did not seem particularly concerned.
Dutch Shepherd - Ptygo (Tee-Go) de las Flores
Rescue GSD - Freyja (Husband's Dog)