Using your last pay stub was probably the root of all your troubles since the amounts you entered did not match what the employer reported. Confirm this by looking at what you entered VS the actual W-2 you got ... this alone can cause a lengthy delay then add in a 4 month covid shut down this can take 6 months or more to work itself out.
In the future do not be in a rush to file ... the IRS is never even processing returns until the end of January and if you have EIC/ATCT on the return they don't process until mid to late February. Complete the return correctly the first time so the IRS has no reason to question anything.
