Ah, I get that - wanting an empirical answer rather than speculation is totally understandable, especially when the question is about something people have a tendency to speculate about already.
I didn’t mean by my question to say you shouldn’t post here by the way; maybe next time specifying that you wanted answers with an empirical basis might have helped contextualize the post - I was worried you might have meant to post in a different community, for example.
https://habitwriting.com/hard-magic-vs-soft-magic/
Basically how much readers are exposed to the mechanics of the magic system, and thus how realistic or constrained-to-reality the magic seems. Harry Potter and LotR are probably more in the soft magic category, whereas Brandon Sanderson’s novels have good examples of hard magic.