I have used TT for years. I started my 2021 return. The program states it can import info from .tax or .pdf files. I browsed for and selected my 2020 pdf file (I no longer have the .tax file). NONE of the info actually imported. I have pretty extensive return, and it's going to be a real pain to re-type all this info! I've never had a problem with this import in the past.
You cannot get very much from a pdf---only the personal information. You need the tax file.
How to transfer last year’s return? https://ttlc.intuit.com/questions/1900883