Possible balancing issue?

Do the safety checks first just to rule it out and check that all wheel nuts are tight.

If its a concentric slave cylinder inside the gearbox i would personally never replace a clutch without replacing it as precaution.

Most suppliers over here can offer a 2 or 3 piece clutch kit depending on make/model. I refuse to even quote on doing the job without doing the lot at once for the exact reason you’re facing. Worn concentric slave cylinders fighting against new clutch pressure plates often leads to tears.

Side note; how much did they machine the flywheel? Is it possible they’ve removed too much material and the slave has over extended?