Strange signal level "vibation" at 40Mhz bandwidth on 911G-5HPacD

RouterOS Wireless Networking
1

On the first image the link is up at 20/40Mhz Ce before 22:00 saturday, after that time is at 20Mhz
On the second image the second link is up at 20/40Mhz before 8:15 sunday and after 14:00, in between them the link is at 20Mhz

There is no interference or noise.

Conclusion: tx-power not stable on 911G-5HPacD at 40Mhz

2

I am seeing the same thing, but using at 80Mhz channel.
netbox-signal.png