Several items can delay the processing of the 2020 return ... some of which are :
> repayment of the PTC
> stimulus credit on line 30 of the 2020 form 1040
> if you used the 2019 earned income for the 2020 EIC &/or CTC/ACTC
> if you have prior year balance dues or unfiled returns
> the info on the W-2 doesn't match what the employer sent in and/or the employer's W-2 is not yet on file
> a variety of other items that require humans to look at
Due to understaffing and over tasking at the IRS again this year many returns will be delayed for as much as months. The aging computer system is being over taxed trying to process millions of 2019 returns and 2020 returns (some of which will need extra processing this year due to the late tax law changes) AND putting out the third stimulus payments. If you want to vent to someone then contact your local congress person and demand they fund the IRS sufficiently so that they can hire enough people and update their computer systems to handle all of the demands made upon this agency. The IRS can only do so much with the continued reductions to their budget.
Please visit the IRS Operations During COVID-19 Help article for more information regarding IRS processing times during the pandemic for tax years 2019 and 2020.