“(derogatory) Biased communication aimed to influence an audience to further an agenda, encourage a particular perception or provoke an emotional response.” (https://en.m.wiktionary.org/wiki/propaganda)

Other dictionaries give similar definitions. The Oxford Languages definition, given by Google, which doesn’t seem to be linkable, says: “information, especially of a biased or misleading nature, used to promote or publicize a particular political cause or point of view.” That’s the only one I’ve seen that does indicate something like the word “misleading”, but even there it is only “especially” information of that sort, not always.

Generally, the word “propaganda” indicates an intent, not an inherent property. Although it is a derogatory term, which people are unlikely to use to describe things they agree with, it is certainly possible for completely true and well-sourced works to qualify as propaganda.

The videos in question are neither true, nor well-sourced, but that isn’t why they are propaganda. They are propaganda because they are produced with the intent of provoking an emotional response (fear and disgust at trans people), of encouraging a particular perception (that trans people are dangerous and mentally ill), and of furthering an agenda (of taking away human rights from trans people).

None of that speaks to whether it is the right decision by the platforms. I don’t think it is, but I also don’t think that the videos should be deplatformed simply because they are propaganda. They should be deplatformed because they are hate-speech and because they are dishonest.