First, the core can be licensed under Commercial or LGPL licensing. This let's non-paying developers use the core in commercial software. This policy was established to ensure trust with the community during one of the many company transitions. For all new modules, Qt evades that requirement by licensing under Commercial or GPL. I have mixed feelings on this.
Second and more importantly, they have started sending aggressive audit letters to customers. I guess that makes sense from a bean-counter point of view where you poke the customer and try to get them to buy more licenses either because the customer actually needs the licenses, or because the customer is afraid to let any dev work without paying protection money. This is a huge pain in the neck for me as a paying customer. They even sent the aggressive audit letter to an old license we have that had not been renewed (or used) in around a decade.
I'll definitely be rethinking my relationship as a customer when the next renewal comes up.