There are times when an em dash can be used in place of a semicolon, but I don't think that's the usual LLM usage. Instead it's replacing a replacing a comma, colon, or period.
Unless you're talking about restructuring your sentences to allow for a semicolon; that's fine.
For example that semicolon could have been an em dash, but I don't think it's the type that LLMs over favor.
My interpretation of LLM em-dash use is that it's like an aside, which is pretty much always going to be weird if converted to a comma since the punctuation was providing un-relatedness information.