Welcome to the forum. There are lots of knowledgeable people here to help out. MFP is right,
please add your location to your profile, (city/state is fine), it gives context to your posts and helps others give you better answers down the road since there are differences between US, Canada and EU bikes, plus California stuff thrown in. That way no one will need to ask in the future.
I haven't experienced this myself. My first thought is to check the battery connections and make sure they are tight. It sounds like the physical shift from accel to decel is causing an intermittent CEL, which limits the problem to wiring, at first blush.
@Jlq1969 - brings up a great point and it's worth checking for codes. That might narrow the focus of the search if it's not a simple battery connection. A wonky fuse that is briefly disconnecting internally could also do this and the code might point to which fuses to check. My thinking is electrical Vs vacuum/pressure mainly because vacuum/pressure changes are softer and those systems are usually more tolerant of short spikes. Air compresses, after all. Whereas electrical connections, severed, no matter how briefly, display immediately and go away just as fast when reconnection occurs. It's probably something simple. These bikes are not prone to gremlins.
@~TABASCO~ is our resident mechanic that has more wrenching hours on the Super Tenere than most and has had the benefits of many customers bringing things to him for repair. He's seen more oddness than any of us riders having only had one or three S10s.
Good luck with the search to eliminate the flashing CEL and let us all know what you find so others can benefit from what you learn.