What does leakage at the filter mean in practice?
The most common causes are a dirty or twisted O-ring, a loose housing, improper thread sealing and excessive pressure.
When does it matter?
Continued work may increase the leakage and cause flooding, so do not mask the leak by simply tightening it.
Which solutions are related to it?
You need to turn off the water, release the pressure, inspect the components and replace the damaged seal; a cracked housing must be replaced.