The reason for this is how release branches work in butler, it's a functional issue and a system I don't intend to change incase it causes people to have to pay again.
in short I have to keep the donation and pulbic separate cause I update them as branches, if i attempted to modify this process i may accidentally cause people to have to donate again to get content. People donated for the $5 verson, thus they have a key to this particular file, i simply update that file to ensure acess. If i make a new branch people who paid may not have acess to that branch, so i'd rather not risk that.
I also simply update these files because people who use the itch launcher get automatic updates. These people will also be seamlessly transitioned into the full game ideally.