There has been some reports from our customers regarding significant Slow WRITE speed on the NVMe SSD detected while the READ Speed is normal. We strongly believe that the issue would be corrected in the next Mac OS update, hopefully.
So far, we do know that Samsung 970 Pro, Samsung 980 Pro, Corsair MP400 SSDs are working well and not affected by the WRITE speed limitation on M1 computers.
You may also wanna have a look at this article here: https://origin-discussions2-us-dr-prz.apple.com/en/thread/253097384
We've tested on 24MAR2022, and the Slow WRITE speed limitation is still there.