Last week upgraded a Chateau Pro ax and a wAP ax from version 7.20.4 to 7.21.4.
So far no issues.
I'm using a standard configuration:
Home WiFi with CAPsMAN - the Chateau and the wAP ax as WiFi APs. I'm using FT and WPA2/3.
SSTP tunnel over which I'm running OSPF to announce my local subnets and receive other local subnets from the remote peer.
BTH server
DoH with HTTP/1 with CloudFlare
I'm seriously thinking moving to the Stable branch... especially if with version 7.23.4 I should be able to run DoH with HTTP/2.