Long story short ... Tate got her nose surgically repaired after her 2016 brawl with Amanda Nunes.

White says he strongly urged her to NOT go under the knife until after her MMA career was seriously over ... because when you're a pro fighter, there's a good chance it could get broken again!

Tate ignored White's advice and got the surgery anyway -- and now that she's returning in July to take on Marion Reneau after a 4-year layoff, Dana's dropping the ol' "I Told You So!"

"I told her don't do it, I'll fix your nose when you're done," White says ... "[but] she did it."

"Her and I haven't talked about this but big mistake and over the last five years obviously she's given her nose plenty of time to heal."

But, Reneau -- the #12 ranked bantamweight -- is a legit striker who will likely take some shots at Tate's sniffer!

White says Tate's a grown-ass woman and she knows what she's getting herself into -- and he's happy to have her back in the fold.

He also dropped some news about Amanda Nunes -- saying Julianna Peña has been "driving me f**king bananas" trying to get a fight with the champ ... and he's leaning towards making it happen.

"[She] will not stop terrorizing me that she deserves this fight. Amanda Nunes this, Amanda Nunes that, Amanda is ducking her, Amanda doesn't want her because the style doesn't match up well for Amanda ... so I'm thinking bout doing a Peña and Nunes."

There's more ... White also talked about this weekend's main event -- Stipe Miocic vs. Francis Ngannou at UFC 260 -- and explained why Stipe could be the most disrespected fighter in MMA history.

"I think he's starting to wear that underdog role and own it," White said.

"I think there's a lot less pressure on him going in there being the underdog. The disrespect continues for the champ."

As we previously reported, the winner will get to face Jon Jones ... White says he'd love to make that fight happen in the Fall.