Not seen this one before. But has hit a couple of my sites today.
Mozilla/5.0 (compatible; Orbbot/1.1;)
From 34.21.92.249
It did ask for robots.txt
Having a quick search, it could be this bot (possibly):
Mozilla/5.0 (compatible; Orbbot/1.1; +http://orb-intelligence.com)
But, that website no longer exists.