pault - as one of those who is probably in your line of fire, I wouldn’t say that there has been any humblebragging going on (I don’t see the necessary ostensible modesty or self-deprecation!)
But in my view, the Prize crossword should involve an element of challenge. The Guardian does indeed offer a wide range of crosswords, from the Quiptic (and now the Quick Cryptic) through the Cryptics which themselves vary in difficulty to the Prize (with the Observer’s Everyman usually falling on the easier side). But the Prize is (or should be) something to aspire to. What’s the point of making it a Prize if it’s easier (much easier, today) than the average? And as I, like most (but of course not all) people, have more time on a Saturday than on a weekday, I do feel rather deprived if the Prize takes me only a very few minutes.
I hope that today was a one-off, as I think the Guardian would be shooting itself in the foot if it were to make a habit of publishing Prize crosswords that are, frankly, easier than the easiest Quiptic, as today’s was.