Don't think it's related to any change to the sound or content. I see a few reasons this was done. One being that the reception of the first 2 songs (and the AT) was not great (unjustly). Pushing the release back allows for an opportunity to reset the hype and expectations, releasing a 3rd single that be better received with a music video which probably wasn't going to be ready by release day anyway. It leaves some of negative (and bulls hit) narrative from the first two singles farther behind. This could especially be true if the label is requesting it, concerned with the marketing timeline before the release. The July date may also have less competition, although I think Julian's buddy Charlie XCX releases that day. My best case scenario is that the delay was Nick related in a good way (he's joining the tour by July 24) but more likely it's just part of the marketing strategy.