The I7 - v7 is another of Mixolydian’s iconic vamps. It’s unique to Mixolydian among the common modes: Dorian shares the v7 but not the I7, and Ionian shares neither.
Just as ii7 is the upper extensions of ♭VIImaj7, ♭VIImaj7 is the upper extensions of v7 — they're twin siblings. v7 is a little darker and more settled: I7 - ♭VIImaj7 vamps have a more bouncy energy in comparison.
Variant note: often, songs will have V7sus chords, which are also diatonic to Mixolydian (along with Ionian), if they want something a little more dominant than v7 but without the brightness of the Ionian leading tone.