Here's the deal ... a troll on the bird app has everyone fired up over a ludicrous tweet he posted Friday -- in which he tries to shade Zendaya by comparing her to Connelly ... but he inadvertently shaded JC too in the process -- and folks are stunned by his measuring stick.

This fella writes, "Any zoomer who thinks right pic is above average attractive doesn't understand that in the '90s, a '7' looked like left pic." In his tweet, he's got a photo of young Connelly next to an unflattering pic of Z ... so already, Sun Optimist is off to a biased start.

He ends with this wild statement, "'Above average' meant something else back then. There'd be like ten girls as or more beautiful than Connelly working at every chain restaurant."

In other words, this guy is saying that young women in the '90s were simply much prettier, on average, than your everyday hottie in 2023 -- and he's using Jen as an example ... by claiming you could find a million Connellys anywhere in America back then. Again, he's also saying Jen wasn't even considered a true dime in this regard ... a few notches below, in fact.

Two things ... he's a jerk for pitting these two beautiful women against each other -- but also ... a lot of people think he's dead wrong about Connelly, specifically. Many say, she IS a 10!

Zendaya is no slouch either, of course, so his entire premise is absurd. In a follow-up tweet, he says the modern "zoomer" thinks heavier-set women are the cream of the crop ... so he clearly has a bone to pick with the conversation about modern beauty standards, etc.

Not to fan the flames on this or anything, but considering Zen and Jen are knockouts in their own right ... we are somewhat curious who the public considers the lovelier dame here.