Not sure if serious. That's how Bayern roll. Nobody got a sniff of the Alonso deal too. Similarly, as far as I remember, Renato Sanches.
This one, though I particularly doubt because Bayern wouldn't want to sell him far as I see. Would be a wonderful signing for City though, just what they need at the back.
You're talking about Bayern buying players, not selling ones. Sure English journalists should have heard of City negotiating for a player like Martinez or something like that.