Summary:

Activating and deactivating dispensers with a one-block gap next to each other creates a glitched, additional water source.

Steps to Reproduce:

1. Place three dispensers facing the same way with a one-block gap between each other (and add an additional block in the gaps and five on each side to protect the redstone)
2. Set up redstone that leads to each dispenser with an optional power source at the end.
3. Activate and deactivate the redstone causing water to flow out.
4. Activate it once more causing the water in all dispensers to go back in.
5. *Optional Step: Cover up water by placing one block in front of the dispenser and two blocks on either side.

Observed Results:

After activating the dispensers for the second time to cause the water to retract back into the dispenser, it seems that an additional water source is created in front of the middle dispenser. Upon checking the middle dispenser's UI, there is a filled water bucket in the slot. Then after covering it up, you need three blocks to get rid of a singular water source.

Expected Results: 

After activating the dispensers the second time, ALL water sources should retract into the dispensers and there should be no water in front of any of the dispensers. And to cover up additional water source, it should only be the source block that needs to be replaced, not the flowing water.

Notes:

This bug was discovered in a Bedrock Realm and retested in a test world revealing the same result.
The files attached show the process and the bug that occurs when producing it.