[Bug] Sky light(ness) jumps

[sepulzera]

Describe the bug
At dawn and dust the light / brightness of the sky(box) jumps.

To Reproduce
Steps to reproduce the behavior:

1. Have a clear look at the horizon.
2. Set ingame time to 23210.
3. Wait just few frames to approx 23215 for the sky light to get suddenly much brighter.

Expected behavior
The light / brightness of the skybox should have a smooth transition without easily noticable jumps.

Screenshots
Screnshot at around ingame time 23213:

Screenshot at around ingame time 23215 (kind of the next frame):

Desktop (please complete the following information):

• GPU: NVIDIA GTX 1050 Ti, also NVIDIA GTX 660M
• Shader loader: iris-fabric-1.9.6+mc1.21.8
• Shader version: 1.3.8
• default shader settings

[Eldeston]

Hello, fixed in 1.3.9, will close this post once it is out