Here's the deal ... J Lo revealed all the celebs who allegedly passed on roles in her recent flick "This Is Me ... Now" in a Prime Video doc about the making of her new album ... and Lizzo's name came up as being "unavailable."

However, Lizzo's singing a different tune, literally. In a TikTok post, Lizzo claims no one told her about the movie offer. She doubles down, claiming she wasn't asked to be in the flick.

No hard feelings from Lizzo though ... she looks into the camera and tells J Lo she loves her. So, she's not really bent out of shape -- but it does raise an eyebrow, no doubt.

Remember, in the 'Greatest Love Story Never Told' doc, J Lo tells her love story through her eyes ... but it sounds like the casting journey was full of twists and turns.

Among the celebs J Lo's teams said passed on the flick ... Lizzo, Taylor Swift, Ariana Grande, Jason Momoa, Jennifer Coolidge, Vanessa Hudgens, Snoop Dogg, SZA, Bad Bunny and Anthony Ramos.

Most of the stars had legitimate conflicts ... Taylor was doing her 'Eras' tour and Ariana was filming "Wicked" across the pond ... but J Lo claims Khloé Kardashian backed out of a cameo at the last second.

Despite her reps saying a bunch of people passed on the project -- two people so far have come forward to refute that ... JC talked to a pap just yesterday and denied any knowledge, and now -- Lizzo's saying she, too, had no clue about this.

Of course, J Lo did manage to bag a couple big names ... including Sofia Vergara, Jane Fonda, Keke Palmer, Post Malone and Trevor Noah.

All's well that ends well, we suppose ... but it is weird that there are two different accounts of this.