I think there's a "fork" or another repo that's continuing the work.

You can search for syncthing on zap store and you'll notice 2 versions.

nostr:nprofile1qqsxu35yyt0mwjjh8pcz4zprhxegz69t4wr9t74vk6zne58wzh0waycpz9mhxue69uhkummnw3ezuamfdejj7qg4waehxw309ahx7um5wghx77r5wghxgetk9uq3wamnwvaz7tmpw3kxzuewdehhxarj9ekxzmny9uk0eua6 is in my WoT ANC recommended the "discontinued" version but I think the other version is auditable enough for you to decide if you want to run it.

I'm not a developer so idk how to verify that the code for that 2nd repo is safe.