I'm not aware of any inherent genetic defects on Corgis.
As a matter of fact they are one of (if not the only) breeds of dogs that actually have normal sized legs that accompany their long bodies.
On the other hand pugs are literally created and born with respiratory and eye problems.
Yes every breed of dogs may have "common" issues (like big dogs and their hearts), but nothing that rises to the level and absurdity of pugs, nor the consistency.
Corgi's can have back/joint issues if the owners let them jump up and down from very high places repeatedly. Where as a pug is just born fucked up genetically.