I think it’s just a combination at this stage. Something for everyone to hate about them.
They’re anti-union. They’re meme levels of expensive in an era of strapped cash. People are conscious of “local” business over something they know is a chain. Brand reputationn for low quality for the price has set in. And lastly people are aware of their stagnation. There’s nothing “revolutionary” going on in the coffee industry to draw customers who have been turned off back to them. Even McShungles can draw people back to them with a special sale on something. Starbucks never does that I’m aware of (and if they do they’re doing a shit job of advertising as evidenced by my lack of knowledge)