If they cashed the check then they got your return. Why do you need to know? It's taking the IRS a long time to process returns, especially mailed returns. They are still working on 2020.
For 2020 returns, Jan 18, 2022 I copied this from an article online...
The difficulty this season – which officially begins Jan. 24 – stems from a massive pileup of unprocessed returns accrued during the pandemic. In her report, Collins estimated the IRS had a backlog of more than 8.6 million unprocessed individual income tax returns and 2.8 million business returns as of mid-December. It also had close to 5 million pieces of unanswered mail. By comparison, the IRS usually enters the tax-filing season with fewer than 1 million remaining items to address.
There are several reasons for the delays. The IRS was grappling with office closures as well as the Herculean task of delivering millions of stimulus checks in 2020 and 2021, all while trying to adapt to major changes to the tax code in the middle of the filing season. The agency is also grossly understaffed; it has 20,000 fewer staff than it did in 2010, and its budget is roughly $11.4 billion – 20% less than it was in 2010, when adjusted for inflation, according to the Congressional Budget Office.
On top of that, more than 20% of the IRS customer service workforce has been unable to work for pandemic-related health reasons over the last two years.
