When did you file 2019? Did you efile or mail it? For 2019 returns they didn't start opening the mail until June 2020 that was stacking up. Back in March the IRS closed their processing centers and stopped processing mailed tax returns. See this IRS page for the latest information
If you efiled....Was your return Accepted? When you efile you get back 2 emails. The first email only confirms the transmission. The second email says if the IRS (or state) Accepted or Rejected your efile.
When you log into your account you should also see the status and if it was Accepted or Rejected, Started, Printed, Ready to Mail, etc. what does it say?
How to access a prior year return
the WMR is only for 2021. did you check to see if the IRS has a transcript of your 2021 return? here's a summary of a thread posted on this forum.
one op reported they filed their '19 return timely and still had not received their refund more than 2 years later. they say they contacted their congressperson who contacted the tax advocate in their state. the advocate followed through and according to what the op was told the return was sitting on an agent's desk awaiting some additional info. the op says they never got the request. anyway once the op provided the requested info the return was processed and they received the refund. so i would suggest that if you filed by the extended due date for the '19 return, contact a congressperson in your state. it can't hurt.
if you mailed your return in a timely manner it's possible the IRS never got it but by proceeding as above you'll find out. so if they don't have it I would refile.