Part of the reason there is some confusion is the term pre-dates the Marxist use of the term, which Lenin originated. Just like how imperialism was a term, but Lenin used it to refer to a specific phenomena of capitalism. In fact I think he originates it in Imperialism the Highest Stage of Capitalism (though he might have used it earlier, I can’t remember)

The original term in the late 19th century was just used for a well paid worker. This is what a whole heap of non-marxist people still use.

The IWW started using it in the early 20th century specifically to refer to professionals like engineers, doctors, skilled craftsmen, who were insulated from the same conditions as other workers. Who would often have guilds, rather than unions. The IWW specifically being Anarchists, Syndicalists, Marxists, DeLeonists and other various socialists, but not Marxist-Leninists. So you also hear it used in some union contexts still. Not that the IWW really is around in any real numbers, but it sort of spread to less radical unions.

Then Lenin uses the term to apply to all workers in the imperial core as is mentioned in other comments here. Despite myself holding to the Marxist-Leninist position I have basically dropped it from my vocabulary due to the ambiguity. I will say well paid proletariat, or imperial core proletariat etc

It’s a pretty nebulous term the roots of which are in Lenin’s Imperialism in which he describes a class of workers that sides with imperialists because they receive a portion of the superprofits of imperial exploration.

Historically it was used to describe business union leadership or union workers more broadly, especially those in the war industries. Further left tendencies tend to broaden the scope of who is a labor aristocrat including professional workers or even the whole of the white working class.

Personally I think as Marxists we need to reckon with the fact that many workers in the imperial core have petite-bourgeois brain worms precisely because their minds have been thoroughly rotted by debt and consumerism subsidized by the blood and sweat of the global periphery. That doesn’t mean we should eschew work among these workers but we should understand it’s limitations.

For instance there’s a massive naval shipyard near me that employs many people (mostly cis white dudes). They have a militant union and excellent pay and benefits. Unsurprisingly they’re all ridiculously conservative and nationalist and I’ve had multiple employees there tell me war would be good for them because it would mean more work and better compensation. Just because many of these workers are union proles does not mean that they will easily align with the interest of the global proletariat and if we are organizing or agitating them we need to understand that.