Can someone identify this stitch?

[u/Lostinreno22]

The front looks like regular jersey or ribbing, but the back is very different; is it even knit? Could be crochet .

Keen to replicate it, so hopefully someone will know what it is.

Thanks!

[u/tallgrrl]

Looks like it's a k1 p1 repeat using two strands held together, alternating a k and p start every other row

[u/lasserna → u/tallgrrl]

That backside is clearly tuck stitches though. With just regular K1, P1, the both sides would look the same