Sync conflict caused losing blacklist data

[MaxHasBeenUsed]

Expected Behavior

Either of:

• Trying to merge two different blacklist into one by default;
• Let users choose to keep one version of blacklist while discard the other;
• A backup of discarded blacklist when conflict happens.

Actual Behavior

When sync conflict happens, the newest version of blacklist (even with only one line) is synced with no popup to confirm the overwrite.

Steps to Reproduce the Problem

1. On device A, write a few line of blacklist (List A) and enable sync feature (Google Drive in my case)
2. Perform a sync on device A
3. On device B, write a few line of blacklist (List B) and enable sync feature
4. Perform a sync on device B, now the active blacklist on device B is List B
5. Perform a sync on device A, now the active blacklist on device A is also List B. Data in List A is permanently lost.

This can happen when: you have a syncing blacklist (List A). But when setting up a new browser environment, you forget to sync the uBlacklist setting before blacklisting websites (Creating List B).

Specifications

• Browser: Firefox Release 128.0.2
• Other extensions/add-ons: Non relavant

[MaxHasBeenUsed]

If anyone else come across this problem, you can always get back to the devices with List A and export/backup it. Or, you can delete List B then perform a sync to avoid conflict.

I always set the syncing interval at maximum value possible since I will never creating one million lines of blacklist on different devices simultaneously. It helped me recover my List A because when I get back to those devices, the list is yet to receive the change.