E0207 always reads unconstrained lifetime parameter in the advanced diagnostics, regardless of whether the unconstrained parameter is a lifetime or type parameter.
The fix seems simple - substitute format!("unconstrained lifetime parameter") with format!("unconstrained {} parameter", kind) in report_unused_parameter - but I don't have the resources presently to get rustc compiling myself to make a PR.
A test for E0207 added in the fix for #35302 enforces this incorrect behavior and would need to also be updated.
Spotted by Sgeo_ on IRC.