For my small library photos, keepass passwords, etc around 30gb, I use syncthing, which will backup on my pc, on my parents pc (they live in another country), on my sisters pc and on my phone. They also use this triangular mode to backup their stuff. Syncthing is setup to only sync through tailscale or home routers network.
So you delete a file by mistake and it replicates within seconds? Not exactly a backup. And a malware will do that to all of your files.
sync is not backup
Also why you sync through LAN only?