Path3D Curve Tilt lerped incorrectly

[jitspoe]

Tested versions

v4.4.dev7.official [46c8f8c] (happens in earlier builds as well)

System information

Godot v4.4.dev7 - Windows 10 (build 19045) - Multi-window, 2 monitors - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 3080 (NVIDIA; 32.0.15.6603) - AMD Ryzen 7 3700X 8-Core Processor (16 threads)

Issue description

When using the tilt aspect of a spline it seems to have a very abrupt turn in and out, so I graphed out the values and noticed that the up vector is directly lerped, but really the angle should be lerped.

This is from a path where the tilt goes from 0 to 180 degrees. The red line is a graph of the up.y. The orange is a graph of the angle. Note how the angle slope jumps up, flattens out, then jumps up again at the end in kind of an S shape.

Steps to reproduce

Add a Path3D. Add 2 points. Rotate the tilt on the end point. Have something follow the path and note that the rotational speed is inconsistent while traveling the path.

Minimal reproduction project (MRP)

test_spline_up_lerp.zip