Does SSG / ServerSideHelpers allow for mutations in getServerSideProps Nextjs ?

Hi, I have a use case where I send the user to a payment portal, and the payment portal can send the user back to my app by either a success URL or a cancel URL. I add different params to each URL to tell my app to do stuff about it. I had the idea to use getServerSideProps to retrieve the params and do the stuff, and afterwards redirect the user to the same page but without the params (such that the whole thing appears as default). I've set up the ssg helper but then I don't see my routes that have mutations. Only the query routes appear available. Is this as intended? Thanks for any help!