Hopefully I can cunningham’s law a more intelligent response, but libel and defamation aren’t “illegal” as in the police will arrest you for it, it’s a civil violation, so the target of that libel would have to sue you for it.

Different countries have different bars for proving defamation. Famously, British media avoids calling drunk people drunk, and instead uses “tired and emotional” or similar, because if you say someone was drunk, but you can’t prove it, you are liable if they sue. Contrast that to the US, where if you sue someone for calling you drunk, you have to prove that they would know that they are lying.

Both methods are subject to abuse, but since suing costs money, it’s more often a weapon of the privileged, so I prefer the US method.

Tamara Rubin is a grifter with no expertise who bought an XRF gun to use to scan random objects as fodder for her blog where she gets money from affiliate links. Her wikipedia page talks about a few of her financial crimes. I wouldn’t worry anything she puts out.