My baby hates his mattress

About a month ago, I transitioned him from the Snoo to the crib. About two weeks ago, I stopped using swaddle-up him because he was actively rolling from back to tummy. Ever since then, he refuses to sleep on his back—he always rolls onto his tummy within a minute after I put him in his crib. The problem is that he wakes up 5–10 times between 12–4 a.m. (I counted).

Over the last few days, he has been hungrier than usual, and I’ve had to breastfeed often. There’s a foldable mattress in the baby’s room, and I usually breastfeed him there in a side-lying position. Yesterday, I accidentally co-slept, and he didn’t wake up a single time—he actually slept through the night.

I’ve always been a bit paranoid about safe sleep environments, but now I’m wondering: does it really matter if my baby keeps sleeping on his tummy and bumping into the crib every night?