New Clutch Fit 7,000 Miles Ago Clutch Feels Light Again?

Nissan Almera N16.

My clutch was slipping in nearly all gears when under load, the clutch pedal itself was always heavy under my ownership.

Had a new clutch fit on 07/04/20 (7,000 miles ago). The clutch felt way lighter, I took it easy for the first 1,000 miles (no hard acceleration etc, it’s an Almera anyway). After a while the clutch had returned to its original heavy self.

Yesterday after starting the car up, the clutch felt light like during the first few 100 miles when it was new.

I have already checked the cars workshop manual and it states Clutch pedal spongy -> 1. Clutch line (Air in line) -> 2. Master cylinder piston cup (Damaged) -> 3. Operating cylinder piston cup (Damaged). Just to get an idea on the possibilities.

I went back to the garage that had done the work and they said that if it isn’t difficult getting into gears and generally the biting point is the same etc not to be too concerned although if it still feels out of order to come back and they will check it.

This is the first time I’m experiencing a new clutch "through" its lifeline, this behaviour just seemed out of the ordinary or is this normal?

Any advice?

Thanks.