The phrase "directly related" is correct and can be used in written English. For example, "The increase in student enrollment is directly related to the university's growing reputation."
The two are directly related.
"It is all directly related".
It's also directly related to stress.
But it isn't directly related to cash.
Weight and health are not directly related.
"This is directly related to Sept. 11," Mr. Spano said.
Mr. Bernier's political and personal setbacks are directly related.
The second reason is directly related to the first.
Others underwrite only classes directly related to the job.
She directly related to the family of George Washington's mother.
That's directly related, in a lot of guys, to concussions".
Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.
Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com