And just to add another tid bit of info since you've been messing around with oil levels. Yamaha uses an oil LEVEL sensor for the oil light, not an oil PRESSURE sensor. So if you think you have too much oil and drain some out, then go for a ride and the oil light comes on, the bike isn't going to burn up. The oil level is low. What this means is that the oil level in the sump is low, not the oil level in the engine.
On this engine design, the engine has only about a quart of oil in it at any given time. The rest is in the sump. And it's being pumped thru the engine any time the engine is being run. So if you have a little less or a little more oil, it just means that the total volume of oil being circulated thru the engine is a little less or a little more. The engine always has the same amount of oil actually in it.
When you drain the oil, there are two drain plugs. One is the engine and it will never drain more than about a quart. The other is the sump, where the bulk of the oil is stored. This is how dry sump and semi-dry sump engines are designed.
The shop seems to be taking advantage of you to run up a bigger bill. And most certainly the ECU claim is bull. Modern injectors don't work that way. Certainly not the injectors on the Super Tenere. I've been on this forum almost since it started and had two Super Tens, a '12 and a '15. With a total of about 150k miles over both of those bikes and in all those years of being active on this forum and ADV and the community in general, as well as the long distance riding community, I have never, ever, heard of a problem with the ECU on any bike causing an injector to be "held open" after the key is off. I'm sure someone, some where, once upon a time, actually had that problem, but it was probably on a ancient Bosch mechanical injection system on something weird like a Saab. And it was probably being diagnosed wrong then.