> taste burnt

It was the case since forever ( ~15 years+ ). Starbucks is not a speciality coffee shop. There is nothing wrong with that. One has to acknowledge that high volume coffee shops have to rely on basically burned beans in order to be consistent with the taste.

Coffee is inherently not a consistent drink. The only brewing methods that don't vary significantly with brewer skill and chance are immersion brews, which aren't broadly used in modern coffee shops. It's surely better to not burn the beans to ash and accept some inconsistency than ruin the drink every time

This

Over roasted coffee averages the flavor across large harvests and sources, and they expect to dump a bunch of sugar in there anyway.