I believe it is a distortion of the ancient and well-known term “salon left” by a Brazilian.
Theoretical disagreements raged among early Marxists. For example, Gramsci asserted that Dialectical Materialism (also known as Marxism) was “the philosophy of action.”
Many socialists at the time, mainly well educated members of the economic and social elites, however, restricted themselves to these “parlor” disputes. They may have won a thousand arguments, but they did not provide any political training or lift any worker out of poverty.
These salon leftists and their Byzantine talks were chastised by the revolutionary and radical left, which was dedicated to propaganda and agitation, direct action, and so on.
Today, the term “left caviar” appears to be more of a derogatory term used to disqualify leftists who, by chance, have some financial security, and is associated with the widely held misconception that a “true leftist” should donate all of his possessions to the poor and live under a bridge or in the desert (this kind of charity is something that religious who want to become a saint aspire to).
The caviar left is a left that lives quite well financially, which is completely different from how working people actually live.
It’s a theoretical concept that’s a long way from reality in the paid world.
There is a disconnect between what they believe in and how they live and invest their money.
They speak in a more radical left-wing tone. And they’re largely on the political correctness side of things.