Having worked at a registrar, these claims always seem suspicious and highly unlikely to me for one good reason: big registrars get thousands (lowballing it) of domain checks every day. There is no way they would buy all the searched domains just to annoy you, it just would not be profitable. I’m also pretty sure front running is an explicit breach of the registry-registrar/ICANN agreements for all TLDs (maybe not for some exotic ccTLDs?) which could cost them their accreditation, sooo… not worth it.

What COULD happen is an insider getting access to the list of looked up domains and selling it or squatting some domains themselves. That would obviously be a reason for termination + legal charges. If I remember well, Namecheap claims they don’t keep a log of the searched domains, but that doesn’t mean it’s not possible for an engineer to intercept it via a backdoor or via internal blind spots (the searched domains could be logged somewhere for some reason).