I've only seen a few remarks form UK folks who criticized the Australian version. Some of it may come down to people not being as invested in the Australian version as they are in the UK version and thus taking on a more favorable view. It may be different preferences in general, I don't know. But UK folks love the current Australian version more than they love their own version.
Even at its worst (OK, not its worst, but its
Channel 10 worst

) I've always preferred BBAU to BBUK, mostly because of the casting.
But even putting that aside, ITV just delivered a historically bad series of BBUK. Not sure if it was the worst ever, because I didn't watch most of the Channel 5 era, but definitely the worst I've ever seen. The casting and the production were both just
utterly dismal. It was clear from the pre-series promo and social media presence, that the producers had already given up. And they spent seven weeks proving that beyond a shadow of a doubt.
(Not like I think I speak for all BBUK fans, but the fact people like
@Brekkie dropped it almost immediately says something.

I'd say 95%+ of the people on Bluesky were hate-watching by the end, although some people took longer to get there than others.)
Meanwhile, this year's BBAU is... fine? Like, I'm obviously not going to be talking about it for years, like some of the OG series. But it shouldn't be surprising that BBUK fans prefer it. Even just the fact there's a proper 24/7 Live Stream, instead of 3 hours a day with
barely any audio, feels like the most refreshing thing in the
world compared to ITV BB.
I also think there's
always been a "grass is greener on the other side" effect with Big Brother. I can remember people on here in the later OG era hating on BBAU and idolising BBUK, while I was enjoying BBAU
way more, in spite of its faults.
ETA: And if ratings are your yardstick for "success", it's also rating slightly better than BBUK, despite us having an extra 42 million people in our country.