What is meant by the Makr of Allah (scheming, plotting, planning) that has been mentioned in the Quran?

“Makr” means to devise for good or evil and this is why it is described by the word “السَّيئ” (bad/evil) in the Quran.

Allah’s Makr

The many verses that attribute “Makr” to Allah refer to his supreme direction and regulation of matters. Since he is the true owner of all management, there is no devising separate from His. Therefore, Allah has supremacy over all planners as it is mentioned in the Quran:
“Allah is the best of planners.”
The Almighty also says in the Quran: Those who were before them [also schemed]; yet all devising belongs to Allah. He knows what every soul earns. Soon the faithless will know in whose favor the outcome of that abode will be. This verse clearly asserts that Allah is the supreme deviser and others’ thoughts and devising will do them no good in opposition to His.