Why are the beds next to my tunnel hatched?

Because Disable neighbouring beds is on for that tunnel: it keeps the bed on each side free for the path, the shade or the snow load, so no planting lands there by mistake.

Those beds show hatched on the Crop Map, so you see at a glance that they are out of production. To grow in them again, edit the block, open the Tunnels tab and turn the option off.

See Add tunnels to your field blocks.