I am having the "sparking blue" issue as well with the backhaul going offline temporarily and then reconnecting again.
When my Zoom calls drop, I physically check the system, and visually can see the remote AP is definitely sparkling blue at the time. The Primary AP's LED is white and working properly. After about a minute it reconnects and the remote AP goes back to the white LED, then everything is fine again.
My wife and I both work from home, so this does cause us to drop our connections during conference calls and is quite annoying.
I bought the system in September 2022 and never had an issue until recently. I have verified that I am not on any channels that the neighbors are using, and they are quite far away anyway. This issue has started happening recently in early December.
When set to Auto this issue happens several times an hour.
When forced to a specific channel the issue happens several times a day.
2.4 20/40 MHz on Channel 1
5 Primary 20/40/80 MHz on Channel 36
5 Backhaul 20/40/80/160 MHz on Channel 132
The RSSI indicates -47 on the remote AP, which is a Great connection. I do not think this is interference at this time, but that the Backhaul just simply reconnects randomly. It is not near any other appliances.
I am using Firmware 3.0.0.4.388_22068 and this is an ZenWiFi AX XT8 AX6600 HW Version 1.