Kelce's big bro, Eagles center Jason Kelce, told the story on "The Big Podcast with Shaq" this week ... after The Big Fella asked the future Hall of Fame center about their newfound fame since Trav and T.S. hooked up.

"It's crazy what it opens up, opportunity-wise. It's crazy to feel how much joy you bring people or how much you affect people's daily lives," Jason told the NBA legend.

Now here's the but.

Kelce continued, "It has drawbacks, for sure and Travis knows more than I do."

That's when the 7x Pro Bowler revealed the reason behind Travis upgrading homes last October (he moved into a $6 million, 6 bed, 6 bath, 16,000 sq. ft. place), saying fans, who weren't invited, were basically camping outside his house, literally forcing him to move.

"He had to completely move out of his house," Jason said, "People were just staying by his house."

Unfortunately, not even the new place, with added security measures, was enough.

"The first day he moved into the new house, in a gated community, somebody knocks on the back window of the house."

Thankfully, no one has seemingly wanted to cause them harm ... but it's clear the Kelce's are still adjusting to their newfound fame outside of the NFL.

"The Taylor World and the pop culture world, that's a whole different level. It's a new demographic that wasn't there before," Jason said.

Sadly, Taylor's no stranger to overzealous fans. She's dealt with over a dozen stalkers, most recently including a man named David Crowe, who showed up to her NYC pad multiple times, despite being arrested.