Your Feature Request

As we already can leverage JA3 fingerprinting in haproxy to do client fingerprinting.

I would like to see a builtin JA4 hash constant for even better client fingerprinting.

Details about JA4:
https://github.com/FoxIO-LLC/ja4/blob/main/technical_details/README.md

What are you trying to do?

Client fingerprinting for Botdetection and the like.

Output of haproxy -vv

2.8.7