Haha, I had kind of wondered about that, until it fully kicked in that it would serve absolutely no purpose.
Interestingly, it appears to just be using a few bytes in user memory to store the brushhead type, if I’m not mistaken. Here’s two TagInfo dumps from two different brushheads, if anyone is interested.
The NDEF record is interesting too. 2/3 of my heads link to philips.com, while the third links to that
Electric Toothbrush Heads & Replacement Heads | Philips Sonicare page.
I’m actually genuinely a bit curious if something like a flexM1 or a flexNT would bother it while you’re brushing. If it loses coupling with the brushhead tag, it would think you just pulled it off completely. It couples pretty close when the brushhead is on though, so I don’t think it could accidentally read an implant instead.