`PointLight2D` stretching/artifacts when using textures with small height

[pmoosi]

Tested versions

• Reproducible since 4.0
• Not reproducible in 3.6

System information

Godot v4.5.beta.mono (7087693) - Ubuntu 25.04 25.04 on Wayland - X11 display driver, Multi-window, 2 monitors - Vulkan (Forward+) - dedicated AMD Radeon Graphics (RADV GFX1201) - AMD Ryzen 7 9700X 8-Core Processor (16 threads) - 61.35 GiB memory

Issue description

When using textures with a height < 32 for a PointLight2D the bottom part is stretched.

A PointLight2D with a circular 20x20 texture.

It doesn't happen when the height is a power of 2 (e.g., height 16 works). It also doesn't happen when using bigger textures and scaling them down via texture_scale.

It looks like this already happens since 4.0, but I couldn't find much about it.

Steps to reproduce

The mrp contains a PointLight2D with a 20x20 radial gradient texture.

Minimal reproduction project (MRP)

mrp.zip