Typically, your credit score won’t affect a VA IRRRL, unless the lender has specific concerns about changes in your credit history.
Because you’ve already qualified, your lender will usually not require a new credit check or appraisal with a VA IRRRL. However, keep in mind that each lender is different and has varying eligibility criteria, even for IRRRLs. They might pull a new credit check if they believe it's necessary. If you currently have poor credit, this could impact your ability to get a VA IRRRL.