Some plastics chemically fail from hair products. Be that as it may...you can repair with thermoplastic - or 3d print an alternative. The company may be aware of this issue and offer warranty replacements. Depending on your aesthetic could repair with gaffers tape...or sugru...or fake sugru (cornstarch and grey 100% silicone caulk - mix to make a putty - allow to dry - it'll feel somewhat skin like but should appear similar - you can also add food coloring for an exact color match...but making grey is tough)

The Q30s on the other hand are solid.

I confirm. The plastic on the headphones body is cheap and won't last long if used daily/often and they might break after a couple of months (into crumbs). The earpads last about 1 year. I owned 2 of these headphones and I'm using glue on the 2nd as there are plastic pieces that broke after only 4 months of heavy use.