Horrible brake noise while rolling back after cleaning

[TonicPH]

Hi guys, have a little issue with my advice 150 brakes after I had a mechanic to do some work on the bike including CBT cleaning and he also cleaned both brakes and replaced the fronts. Now, after I roll the bike backwards and press the brake, front and rear, they make a horrible noise. At first I thought it will go away but it didn't so I have taken the front brake apart next day to inspect and reclean everything. He did use the CVT cleaner on the brakes which I though could leave a residue on the disc surface? Reassembled everything and it was so much better, however one day later we almost back to same thing. Could it be possibly stuck piston causing the brake drag and noise??
Literally sounds like a bloody trumpet
Sorry can't upload video, link instead:
https://youtube.com/shorts/MMHdU4fHPkQ? ... 1M15FAAWAM
Thank you!!

[TonicPH]

CVT not CBT sorry