Neither, as they are bulk roasted/over-roasted cheap robusta beans from a high street chain
Good High St chains don’t use robusta.
I end up with a few grounds in my coffee when I make it, I think it comes from the odd bits of grounds stuck to the basket or machine. If there’s some on the lip of the basket or the seal, and there’s too much in the basket the coffee sometimes overflows slightly around the seal and I get some that way. Never enough to affect the taste though, I’m talking traces, not even a whole pinch worth.
In your case I’d say it is likely to be the state of the seals in their machine.
Better preparation brings out more flavours and more nuance of better coffee. Imagine pop music played on a cheap radio, vs an expensive hifi vs Beethoven on an expensive hifi.