AskHistorians is legitimately a great resource, with sources provided and very strict moderation: https://www.reddit.com/r/AskHistorians/comments/pu1ucr/tiana...
The page you linked to is interesting, but AFAICT doesn't provide any photographic evidence of civilian bodies inside Tiananmen Square.
The source for that is a diplomatic cable from the British ambassador within 48 hours of the massacre saying he heard it secondhand
It would have been too soon for any accurate data which explains why it's so high compared to other estimates
I recently read a bit more about the Tiananmem Square incident, and I've been shocked at just how little evidence there actually is.
It's funny that when the Israel government posted some photos of the Oct 7 massacres, people are very quick to point out that some seem staged. But some bloody photos that look like Tiananmem Square from the 80s is considered definite proof.
You do raise one good point however - propaganda in the time of Tiananmem was much, much easier before the advent of smartphones and the Internet. And also that Israel is really, really bad at propaganda.