I thought it was the ASA that did all the advertising stuff, but apparently there's an extra layer of bureaucracy, with it being the Committees of Advertising Practice (CAP) being the ones to decide what is allowed or not. The CAP has decided to ban
"gender stereotypes that are likely to cause harm, or serious or widespread offence".
This ban will include men struggling with household chores (understandable) and girls being less academic than boys (here, I'm not sure I've ever seen such an advert).
There are some grey areas they are considering, such as a man relaxing while a woman cleans (this is the 'agreement' for certain households, I'm sure, and there's nothing intrinsically wrong with that, or the other way round if the couple agree), situations where someone fails at something due to their gender (I'd support banning this, no product should be claiming someone is a failure due to their gender) and adverts that belittle men for doing 'female' tasks (I'd support banning adverts that attack people happily doing something they want, but then that's what most advertising relies on).
Obviously they can't ban all stereotypes, otherwise we end up with the same stereotypes but with the other gender as the media tells only men to be the primary caregiver, and women only to do STEM. But a lot of adverts are really stupid and need sorting out.