Semi-recently, some Russian users experienced problems accessing iNat due to what seemed to be ISP-level blocking.
In this kind of situations, using a VPN is usually suggested. Yet somehow nobody seems to realize that Tor is essentially a safer and free VPN. Safer because recording an individual user’s online activity is much harder for Tor nodes’ operators to do than it is for a VPN operator.
In any case, I haven’t used iNat since May due to the blocking. It was nice while it lasted.