What does it mean in American?
Laid off means the role won’t be backfilled. It could also mean the role was renamed, and they wanted to let the employee go but it looks better for everyone to say it was a layoff.
Let go (at least to me) could mean either.
Just because they were fired for cause doesn't mean the company wants to keep that job around afterwards.
That said, it is unusual not to say 'laid off' these days unless the person was fired for cause, but the recently media frenzy around the term might have them saying other things instead.
Reminds me of Bill Lumbergh in office space, "so if you could just go ahead and [thing Peter Gibbons really didn't want to do]".