2015 Volkswagen Tiguan - Lags

78k miles always serviced on time and at dealership. I have always used premium gas (91 or higher is required). I have a very slightly noticeable sensation upon starting the car, and again at the 20-30mph range. The car feels like it’s lagging in the transmission. When I put the automatic transmission gear shifter over to the ‘manual’ shift mode, it’ll read that it’s all the way up in fifth or sixth gear. Aside from that, it runs well. No maint. or service lights, $79 diagnostics reveal nothing. Dealership states the injectors probably have carbon build up on them and need to be cleaned (about $800 with labor ).

Your question is what, the need to do this injector clean? I’d say $800 seems pretty high for this. An independent shop could likey do this cheaper.

Seems more like the transmission is shifting way too soon.

A good friend of mine was “given” VW Passat of similar vintage by his daughter who drove it for 100K mile or so and then made a “gift” to her DIY-er dad.
It also had some “lag” issue, which he traced to transmission (after eliminating other engine-related possibilities).
At first, he wanted to simply replace the fluid and see what is gonna happen, but it did not help, so he spent some time searching through VW transmission-specific info, and found that at least on Passat, the transmission valve block tends to collect the fine metal particles around valve solenoids, which make them stick and transmission to “lag”.
So, valves block was removed and he indeed found that issues, but it was beyond simple repair and new valve block was way too expensive, so he ended up assembling everything back and trading car.
Hopefully, @LoriBitely problem would resolve with something more simple than that, but I would not be surprised to find transmission to be the problem