I'm on a Samsung S20 FE with Android 12 and, like Josue, was also able to have dark mode change (enabled and disabled) trigger an action. Have you tried having just a simple action like "torch on" to see if the trigger of dark mode change is really the issue?
I just started with MacroDroid today and am having a lot of fun seeing all the possibilities I can automate! If you still have any keys, I'd really appreciate a pro version! Thank you for doing this either way!