I have owned these headphones for about 9 months and today while traveling in public transportation my bag was smoking, these headphones suddenly started to self combust and melt.
I really don’t know how something like this can happen it really looked like that chip was just burning.
There have been plenty of news reports on this for many years. Lithium-ion battery failures are nothing new and everyone should be aware that they can happen. There's plenty of videos of exploding vapes, e-scooters, etc. They are rare, but they do happen. They're more likely to happen with very cheap products or with very cheap chargers (the chargers are a bit less likely because a good product should have over voltage and over current protection...or at least over current. These can happen from physical damage, shorts, manufacturing defects, water damage, etc.
Keep in-mind that the vast majority of consumer electronics with lithium ion batteries have off-the-shelf batteries that are not made by the brand of the actual device.
No brand is immune to this. Again, you don't typically need to worry, especially when buying decent-quality electronics, but everyone should be aware that this can happen.
Source: test engineer for a major gaming peripherals brand. I've seen a few of these myself on extremely rare occasion (they are treated extremely seriously as you can imagine).