Here is a raised bed that existed when I moved into that house. I do not know how long it had been in existance when I moved in. I liked it because I could work in it without bending over. It was broken up into two sections. I took the lattice off because I don't like lattice
This second section did have some bowing you might be able to see. I did not construct it so I don't know what could have been done to prevent this