If you're using wayland, gammastep.

Have you considered using Redshift manually? Here's what I do:

First, uninstall redshift-gtk and just install redshift.

Next, according to redshift -h

The neutral temperature is 6500K. Using this value will not change the color
temperature of the display. Setting the color temperature to a value higher
than this results in more blue light, and setting a lower value will result in
more red light.

Default values:
Daytime temperature: 6500K
Night temperature: 4500K

So, create two scripts, for example "Redshift-On.sh" and "Redshift-Off.sh". In the former copy and paste:

#!/bin/sh 
redshift -P -O 4500K

and in the latter copy and paste:

#!/bin/sh 
redshift -P -O 6500K

In my case, I create custom menu items (Mint's menu editor) and link them to those scripts so I can run them from the main application menu/ add them to my dock.

Never used it but found this on the archwiki https://github.com/jumper149/blugon. Weird that redshift isnt working for you, it worked great for me when i used it

Using hyprland+nvidia, I've had good luck using this screen_shader command:

hyprctl keyword decoration:screen_shader /path/to/flux.glsl

Where flux.glsl is

// blue light filter shader
// values from https://reshade.me/forum/shader-discussion/3673-blue-light-filter-similar-to-f-lux

precision mediump float;
varying vec2 v_texcoord;
uniform sampler2D tex;

void main() {

    vec4 pixColor = texture2D(tex, v_texcoord);

    // green
    pixColor[1] *= 0.855;

    // blue
    pixColor[2] *= 0.725;

    gl_FragColor = pixColor;
}

wlsunset on wayland

I use Iris Micro, I've never had issues with it.

i use SCT or XSCT from the commandline. its in the debian/ubuntu repos. here are some other ones