UTC+2 isn't very convincing as an argument for Russia. Only the Kaliningrad exclave uses that timezone, and if I were in a state-backed group, I'd live in one of the big cities.

Also quick search suggested UTC+3 was seen during the summer, and Russia doesn't do DST either.

Edit: some of the UTC+2/3 times are attributable to being differences in git committer and author dates (e.g. email patches)

I couldn't let this be, so I went through the commits and as far as I can tell, that's the case. The committer/author names and timestamps are consistent with using --author on a commit (... or in a few cases, --amend --author).

Except one: commit 3d1fdddf9 has Jia Tan as both author and committer but the author timestamp is in +0300 while the commit timestamp is +0800.

I’ve always found this an amusing method of attribution considering top tier hackers are unlikely to be writing code only during office hours.