HTTP Error 403.16

Windows 11
IIS 10.0.22621.1

Some locations are being asked for an authentication certificate (for example my workstation), my co-workers work station is not being asked for anything.

This isn't a big deal I can click "don't send a certificate"  and continue on. IN the IIS manager the SSL settings is not required and client certificates is set to "ignore, my very limited understanding is this pop up shouldn't happen with those settings.

The other issue is we have some customers that are getting a HTTP error 403.16 error
I can't reproduce this error myself.

Hoping someone could point me in the right direction.

Thanks