There is a spectrum in sugaring all the way from escorting (pay for play dating) to trophy wifing (wife is young, pretty, doesn't work, and lives from her husband's income). Is an escort a sex worker? Yes, of course. Is Melania Trump a sex worker? Most people would say no.
There are a lot of men here who treat sugaring as escorting. I don't. I'm not saying I'm better, I just prefer more relationship-y sugaring. That means I'm monogamous, aspire to long-term, provide the PPM/allowance even in cases where we don't have sex (and this always happens at some point), and usually catch some level of feels.
So no, sugaring is not sex work in the way I do it. But I would never look down on an escort or john as long as they're not manipulating, lying or using people.