If you just bought it new, take it back to the dealer and tell them that the floor isn't acceptable under the shower. My 2015 Jayco 29QBS had a plywood floor under 2/3s of the shower pan. If you stood close to the wall, it flexed a LOT. I ignored it for a while, but the flexing eventually loosened the drain connection and flooded the undercarriage. Took it back to the dealer, had them dry out the floor, remove the shower pan, fix the floor for full support and its been great ever since then.
2015 Ram CTD
2015 Jayco 29QBS