In English "reason" is not followed with the preposition OF.
FOR is used instead.
Probably it is easier to use "of" for Russian speaking people but it is not correct.
What is the reason for an engine failure?
The reason for an engine failure was ingestion of a foreign object.
The reason for this disaster was an engine failure, not human factor.
Frankly speaking, I don't understand the reason for this delay.
But there is a collocation "FOR THE REASON OF" (под предлогом, для того чтобы, по причине) where we use OF.
He became a pilot for the reason of flying to different countries free.
IQOS cigarettes are not allowed during the flight for the reason of safety.
