i thought XM2 can use up to 10years if haven't botak ?

Hahaha, I changed a pair of my XM2 at 6 years old of about 110,000 km with 2 mm thread depth left.
According to an image (from Continental Tyre) I uploaded here before, in allowing up to 10 years usage post production, I could have prolonging its usage till 1.6 mm left fully complying with tyre manufacturer/association requirements.

Yes, it hardened.
Not only that , it hardened 'severely' at 6 years/110,000 km usage, indeed.
Hardening of tyre in itself (whether in use or in storage) , is never a criteria of discontinuing tyre service ......
as is often expounded as 'truth' in this forum, which I consider as myth as due respect.

Continental says :-
[attachmentid=9325179]

Continental only recommends, but it never requires , tyre replacement 10 years post manufacturing.
Check with a loyar burok friend meaning of  : recommends vs requires.