Well, yes, colonialism is a major issue in the modern history of China; China acts like a colonizer towards its border territories. There's something fascist about ethnic cleansing, about re-education camps, about disappearing citizens without habeas corpus, about killing religious prisoners and harvesting their organs.

We can have both truths; it can both be true that China suffered greatly under British colonialism, and also be true that China is committing dire human rights violations which, to the degree that they further a Han Chinese ethnostate, are fascist. Tibetans, Uighurs, and indeed the people of Hong Kong are suffering under China's policies.