"Financial grooming" is the term in common use in the UK.
I've never heard of 'pig butchering' which sounds rather victim blaming and certainly would not be used as a *descriptive* term by UK banks, government or media.
I'm also in the UK and I'm not seeing the victim blaming part of it. I don't think it's a great term, given that I had no idea what it meant until I read the article. Then again, I would have assumed "financial grooming" was a service offered by a concierge banker to lower my direct debits. Out of the two phrases, I do feel that saying "my uncle is being butchered" will get law enforcement to act more quickly than saying that he's being "groomed".
I'm obviously missing some context or nuance here, since you're the second person to identify the connotation. Is it the "pig" part?
I'm obviously missing some context or nuance here, since you're the second person to identify the connotation. Is it the "pig" part?