>data harvesting to the government having access to said data - is true for western companies as well and that should be the problem
Very much this. As a European who doesn't intent to set a single foot in China, I'm much more comfortable at the thought of China having my data than my own government.
What if your government gets the data anyway? Hackers could hack TikTok servers and release data or sell to interested parties. Your government may already be tracking your TikTok usage by sniffing traffic on intermediate servers or other measures. Or China may even sell or share this information (or worse, manipulated false information) for strategic purposes.
