Please add this functionality as an integral part of Plasma: https://store.kde.org/p/1387238 It is very handy to be able to automate the change of theme according to the luminosity in the environment throughout the day: it is not the same to work in the morning than in the afternoon or evening, and switching themes by hand every day is a real PITA. This applet has several limitations (you can not freely choose the color scheme from all you have, the change occurs every 3 hours...), also seems to be abandoned, but the idea is very good, so I suggest that it is implemented in Plasma. Perhaps this could be added to the Night Color KCM module. And another nice feature for that Night Color module would be to also be able to configure an automatic screen brightness change using the webcam as a photometer. Translated with www.DeepL.com/Translator (free version)
Sorry for the advertisement, I didn't realize that Deepl's copy button included that line, and I don't see how to edit mi former post to remove the spam.
*** This bug has been marked as a duplicate of bug 408563 ***