I just found that my passport expired in 2020. Online renewal is not currently available, so will renew by mail. What has your recent experience been with turnaround time?

Sorry I can't be more specific, but my husband sent his in sometime in late February (I don't recall the exact date USPS tracking showed it was received), but he hasn't gotten his renewal yet. This was non-expedited.

Passport renewal - Fodor's Travel Talk Forums (fodors.com)

I did nothing to expedite the process. Just over 10 weeks from confirmed delivery at the Texas processing center in February to delivery in my mail box this week.

I didn't receive any updates until the notice of return delivery. If I hadn't received it this week, I planned to call the 800 number and inquire.