https://www.nytimes.com/2018/08/13/us/politics/peter-strzok-fired-fbi.html
"Mr. Strzok was accused of sending a highly sensitive search warrant to his personal email account."
"In addition, the inspector general said that Mr. Strzok had forwarded a proposed search warrant to his personal email account. The inspector general said the email, which included a draft of the search warrant affidavit, contained information that appeared to be under seal."
Notice Strzok's lawyer doesn't really dispute the fact Strzok violated FBI policy either.
Trying to say this was politically motivated is just lazy.