Src. Address out of range

Hi,

I see connections in the firewall where the source address is not part of the range of my DHCP server (192.168.8.0/22):
Capture.JPG
How is this possible? I have ~5k connections right now in my firewall and almost all of them are from within my DHCP range but, as you can see in the screenshot, there are connections from IP like 10.136.200.81 that are not assigned by my router!

Any idea?

Thanks!