How are you storing passwords and 2FA keys that proliferate across every conceivable online service these days?
What made you choose that solution and have you considered what would happen in life altering situations like, hardware failure, theft, fire, divorce, death?
If you’re using an online solution, has it been hacked and how did that impact you?
That used to happen to us before we started using SyncThing (and before we had data plans on our phones).
By the time we migrated to it, we had a home server running 24/7 and this ensured that at least one device in the chain was always online, had the latest version of the database, and pushed it to other devices as they came online. Our phones also have data plans now, so things generally sync in realtime which helps avoid issues.
If you don’t have at least one always-online device, I think the next easiest way to avoid sync conflicts is to modify the database from one designated device. That way even if a conflict does arise, you’ll know which device is always correct.
For resolving the conflicts, I would open both databases, sort by modified, and review the latest changes in each.