To me it is not 100% clear if your IP is always hidden
This community post talks about mixed results although it says that issue was fixed
A quick Google search and many sites say that warp does not hide your IP altough some say that they added that feature
However this post and this post from the cloudflare team says it does hide your ip.
Cloudflares blog posts say so so I assume this is true but I would still recommend everyone to verify this for themselves before receiving letters from law firms.