Are you sure it was the Federal refund you got and not the state? The IRS was not been processing mailed returns and is now working on the backlog that's been stacking up. They are opening the mail in order so if you mailed in July it should take a long time for Federal. See this IRS page for the latest information
https://www.irs.gov/newsroom/irs-operations-during-covid-19-mission-critical-functions-continue
Almost Everyone who mailed has been getting their state refund first.
