The documents regarding former Prosecutor General Andriy Kostin's alleged visits to Russia during the war are fake. This was reported to UNN by the spokesperson for the Prosecutor General's Office, Nadiya Maksymets.
Since 2014, Andriy Kostin has never been to Moscow. The screenshot spread on the Internet is a fake
Addendum
Earlier it was reported that a number of Ukrainian ex-officials, including Kostin, allegedly visited Russia more than once during the war. This information is contained in scanned copies of documents of the Russian Federal Security Service's border guard service leaked to the network.