GFCI outlet trips from any heating element
If your vacuum sealer is like mine a plastic case with a 2 prong cord there is not a way for a ground fault , I would say that since you have 2 devices causing tripping and this has worked in the past. the GFCI is failing. I started using weather resistant GFCI outlets in bathrooms quite a few years ago because bathrooms can have very high humidity levels and the outlets being in walls can sometimes condense moisture similar to being outside. I don't normally use WR GFCI'S in kitchens because they are normally larger rooms and not exposed to such high levels of moisture. I would swap out the GFCI. The new ones have more sensitive electronics and constantly self test where older ones I have found failed (test won't trip on outlet or plug in tester) or trip for no good reason like a double insulated device with a 2 prong cord, so this should solve your problem.