It's not just Tinder. Apparently, the Russian communications regulator has a list of 175 online services operating in the country that are required to keep six months of user data–including DMs–to furnish to Russian authorities on demand.
Failure to comply results in blocking, as LinkedIn recently found out. The AP reported that Zello, a voice messaging app popular with Russian truck drivers, was also blocked.
The truck drivers had previously used it to mobilize protests against a new toll system in 2015.
Authorities claimed that messaging app Telegram being used by extremists was also on the chopping block, but it's still available.
Facebook Messenger and WhatsApp aren't on the list.