I see @bdamico installed some pine boards between the bottom and the tray that sits above the bottom for stiffening in his build thread
https://www.garagejournal.com/forum/threads/blue-saber-cabinet-install-review.169972/.
"In any event, the bottom panel is like a tray. I thought it was a...
Usually Saber cabinets are floated on the wall with support from a rear stem wall or 2x6. I'd like to have a little bit more flexibility in being able to re-arrange my garage as part of it also doubles as a shop. I've had to reconfigure things in the past...plus if I move would be nice to easily...