Is it indeed? There are actually some pretty clear practices that I think one could certainly suggest that the Muslim faith is not 'celebrated' in Xinjiang or in Hui areas in Gansu, Ningxia etc. One thing that comes to mind are the restrictions on fasting amongst students, government officials (including teachers), Party members (which includes a lot of fairly 'normal' people, not just officials). The Arabic script, which Muslims worldwide would be familiar with, is largely discouraged from use in places like Ningxia and Henan, where you have a lot of supposedly Han-ified Muslims known as the Hui. The logic is ultimately that if Muslims live in China, they should be at least somewhat 'Sinicized'. Why this rustles feathers is that even under Mao, where there was certainly a lot of violence against religious institutions (a lot of it justified, of course), there was also a lot of insistence on the necessity for Han people to not pressure ethnic minorities to also necessarily act like the Han. This meant that there were practical limits on Han migration to ethnic minority areas, more employment opportunities in local Party bureaus for minority cadres etc. But following the 80s in particular, a lot of that got tossed out of the window. There is a reason, imo, that violence and separatist tendencies in Xinjiang began in the late 80s - the Han population in Xinjiang had rapidly increased. And it has continued to increase.

There are some elements of cultural erasure that comes with this sort of population manipulation. Yes, Uyghurs learn their language. But the emphasis has changed in some pretty pointed ways. In a lot of 'bilingual' schools, where Uyghur was once more dominant or at least taught in a fair amount of classes, it has become somewhat circumscribed as a specialty subject compared to Mandarin, which has gained more of an outsized importance. Bearing in mind that, one of the core tenents of the early PRC's constitution was that autonomous regions could maintain their own educational standards and policies, and I think it makes sense that people are upset. I would also argue that policies targetting 'fundamentalism' are somewhat misguided in that we have to also understand what the source of fundamentalism is. The Chinese government currently uses the language of 'war' and 'terror' (where did they get that from..) to describe its attitude towards fundamentalism. The argument is that ultimately foreign madrasas and 'Islamicization' has eroded what was previously a secular culture, and poses a threat to China. But in my opinion, as with fundamentalism in the US or Europe or wherever, 'Islamic' terrorism is ultimately caused by socio-economic factors, namely the economic transformation that has happened in Xinjiang since the reform era, coupled with changing demographics. There is a reason that even Hui people, who again are supposedly much more 'Chinese' in their outlook, have also been recently targeted by anti-terror measures. Perhaps fundamentalism is growing, but it is as a consequence to what was a fairly flawed policy of the central government trying to shore up its presence in the periphery in a way that even local officials have grumbled about.

It's a question of if pushing cultural hegemony onto a population is an acceptable thing at all, and to what extent it is okay for indigenous populations to fight against that.

I don't aim to make any one judgement, but even from within a generally leftist world framework there is a legitimate case for the situation there being either a good thing or a bad thing.

When this stuff comes up it's important to not be allowing lies to go through like what Zenz does, furthering jingoistic thinking in the west, but there's definitely a respectful critical policy debate leftists should have about imposition of cultural ideals on indigenous populations.