as mentioned before, f.lux stopped working after installing latest nvidia driver yesterday:

NVIDIA 31.0.15.5161: NVIDIA Quadro K620 (20240215)

PnP-Monitor (Standard), 528 x 297mm, built 2017
Chromaticities:
R=0.653320 0.334961
G=0.323242 0.611328
B=0.153320 0.061523
W=0.313477 0.329102
sRGB gamut: 93%, AdobeRGB gamut: 65%

Unlimited gamma ramp=1, Internal ramp=0
Monitor 1 on NVIDIA Quadro K620
Has VCGT profile=0, Gamma Ramp works=1

Windows Build: 19045.4046

It's a pity .....