Godot 4.6 user.
GPUTrail3D has an interesting glitch. Pre Godot 4.6 version (4.4) this glitch can be solved by using a delay of 0.02.
But in 4.6 it behaves differently.
4.6 with current version of GPUTrail3D (17 feb 2026) will show a glitch at the first trail only, if you set the delay to exactly 0.03. After the first glitch it works flawlessly.