Of course, we're talking about 'Babylon' -- which hit theaters this holiday weekend ... and only raked in a meager $3.5 million domestically through Sunday, with an estimated $5.3 mil expected to come in through Monday. Either way ... it's not a good turnout whatsoever.

The movie -- which is about old Hollywood and the emergence of "talkies" -- had massive star power attached to the credits ... in addition to Margot as the lead, it also featured Brad Pitt, Tobey Maguire, Olivia Wilde, Chloe Fineman, Eric Roberts, Flea, Max Minghella, etc.

Plus, there's the director -- Damien Chazelle -- who's an Oscar winner ... and with a somewhat hefty budget of $80 million (and a lot of marketing) it's unclear why this one didn't do well with moviegoers this holiday season. The mixed reviews probably didn't help.

Interestingly, there's another movie Margot was a part of earlier this fall that had very similar vibes -- another star-studded lineup (Christian Bale, Robert De Niro, Rami Malek, Taylor Swift, etc.) that came together for 'Amsterdam' ... which also flamed out in theaters.

It only made about $6.4M during its opening weekend in Oct., and went on to collect just $16M or so domestically overall -- this after yet another $80 mil budget spent to make it.

Bit of a tough year for Margot on the film front -- not only were things meh at the box office ... but she also said the 'Pirates' movie she was attached to had been killed by Disney -- even though one of the producers for the franchise insisted that's not quite the case.

She's got a lot on the horizon for 2023, though -- MR's already set to star in 'Barbie', as well as a Wes Anderson flick, 'Asteroid City,' ... not to mention her own 'Ocean's Eleven' prequel. The only (potential) problem ... all of those will have super stacked casts too.