The CCP are so dishonest we have no idea what even happens to most of their prisoners. It is likely China executes the most prisoners in the world.
You are comparing apples and oranges.
China is the #2 economy in the world. America is constantly whining about the #1 economy in the world, why would they not also whine about #2? The truth is that there's nothing unique to Americans complaining about China. A lot of what Americans complain about China is quite similar to what they complain about America. This is especially true with authoritarian sentiment, with the fear that China will be the model used for the US against themselves. Yeah, there's a few "fuck China, America best" but I'd be shocked if the was anywhere near the mean or average sentiment. People are more complicated than this and Americans are just vocal about everything. Because they're so vocal, it is easy to ignore some things and pay attention to others, especially when they validate your internal biases (such as complaining about your country, which is nationalism).
I think it's the broad, off-topic, pro-China/anti-US comments, like this that make people feel like it's probably a bot or human equivalent.
If the post was actually a reply or rebuttal to any of the comments content it probably would give that vibe.
Tiananmen Square?
This is a very tough argument to make given how China has very little freedom of press, speech, association or information.
A fundamental misunderstanding of how people think. But they tie their identity to their own government so completely they are literally blind to the rest of the world.