I am performing a pentest for a client. I tried to brute force into his app and I've been blocked. All good and normal so far. I changed my IP address using a VPN client. But still, the Kali Linux is blocked. Oddly enough, on my Windows machine on which the Kali VM is running, the website is working fine.

Both machines, Kali and Windows exit on the internet with the same IP address, so why Kali is not working and Windows is working? How do I fix this as I am not able to move forward with my pentest?

Any explanation as to why and how I can bypass this?

Just to enumerate some workarounds I tried:
- using a VPN to change my IP
- using different browsers
- using Incognito mode