I've restarted probetest to see if the situation improves.
Looking at the graph there is a slow increase of unknown NAT proxies and decrease of restricted for the last 10 days. Other times that probetest has failed the increase was more steep.
Quoting alertmanager@hetzner-nbg1-02.torproject.org (2022-05-03 20:17:13)
Total firing alerts: 1 Total resolved alerts: 0
## Firing Alerts
Time: 2022-05-03 18:16:30.286335746 +0000 UTC Summary: There is a problem testing the type of NAT of our proxies Description: There are only 2.0 times proxies with known NAT type than with unknown
##Resolved Alerts