I can't play on the new snapshots, help.

Hi! The nether update is coming out and i want to play, in my server, on the new snapshots, but there is a problem... When i try to update my server to a new snapshot it says that i can't do that if i don't reinstall my server but i don't want to lose all my stuffs. It's been a few days since this problem came out so, can someone help me? (i'm blocked at the 20w14infinite snapshot).

If i make a backup,and then upload it, it brings me back to the version which i made the backup.

If i download, and then reload in a new version my world, it erases all my progresses.

I noticed that if i try to put another version, even the 1.15.2 or even an old one, it says that i have to reinstall the server anyway. So the problem persists for all version not just the new snapshots.

if i want to update to 1.16 (when it comes) will i have to reinstall the server or can i update without problems?