Miley Cyrus performs at Sunny Hill Festival in Pristina, Kosovo Friday, Aug. 2, 2019. Picture: AP

Miley Cyrus told Brody Jenner to "take a nap" and "cool down" after he responded to pictures of her kissing his estranged wife.

The "Hills: New Beginnings" star joked he'd be going out "holding hands" with the "Wrecking Ball" hitmaker's estranged husband Liam Hemsworth - who she announced her split from over the weekend - after the "Black Mirror" actress was seen getting close to Kaitlynn Carter on vacation.

Liam quipped: "Watch out! Pics of Liam and I holding hands on the beach coming soon"

Referencing a memorable moment on "The Hills: New Beginnings" when Brody spent the night in his car after a row with Kaitlynn, Miley replied: "Go take a nap in your truck and cool off. #HotGirlSummer. (sic)"

Meanwhile, a source previously claimed Miley and Liam's split isn't "surprising" to friends as an insider insists the couple still had "a lot of issues" despite appearing to be perfect.

A source said: "This split isn't shocking to people who are actually with them every day.

"After they reunited, everyone thought they were this 'perfect' couple, but they still had a lot of issues. They're not on the same page when it comes to a lot of fundamental things that make a relationship work. It's not surprising at all."

Whilst another source added: "They have been trying to make it work for months now but haven't felt they were connecting on the level they were feeling when they got married last year.

"It's been a rough year. She has been ready to put out music and be back in the game touring and performing. They really grew apart. Miley and Liam have still been communicating and it wasn't a messy split but they have decided they are at different points in their lives currently."