My mom had lots of surgeries in her life. no reaction to general anesthesia ever. lately last 2 surgeries/procedures my mom had she either had a hard time waking up or her face swelled up. can allergies just happen years later? is this likely genetic?

Not all anesthetic drugs, whether inhaled or given IV are the same. New ones come along & add to the list of those available. Facial swelling is not by itself specific to any product, but may reflect a reaction to the material that came in contact with her face during any part of the procedure. It would be good to report the reaction to the treating physician. They can track down a likely cause.