I have few NAT rules and observed it on both game server and web server.
When someone visits the website or joins the server - logged IP is LAN gateway's IP and not client public IP (in server logs).
If I enable logging of NAT rule then it logs proper public IP of client in router log.
It seems like some issue with RouterOS or hardware/software limitation.
I have 2 routers, one from ISP and second is mikrotik's.
Direct connection to ISP's router keeps public IP of client unlike through mikrotik.
The issue is probably not PC as it works as expected when connected directly to ISP router.
RouterOS version 6.48.6 or 7.9 does not make change to logged IP.
Connecting through public IP assigned by ISP.
Configuration (simple, 3 bridges, one wan active):
https://pastebin.com/C9fa4W6e