I think it was abundantly clear that the queen didn’t like Harry and Megan’s behaviour, from the infamous recollections may vary to her statement on them leaving saying it was her families hope they’d basically settle down, as well as the fact she clearly said no to many of their requests, inc the half in half out.
I can only imagine how horrified she must have been when she saw Harry at the Africa tour, where he was representing her, use that as his platform to make a statement about him suing the press, and their petulant behaviour on that tour,
so I think using her personal nickname, then lying about asking her permission, might have been something that seriously pissed her off.