I think "supports" is a bit incorrect wording. Change Block Tracking in a proper sense, like it is used in VMware appeared in Hyper-V 2016 as the RCT feature, full stop. Now when issues with Hyper-V 2012 backups became apparent but support for a proper CBT was not available, every man and his dog come up with "proprietory driver" to make those "CBT"-type backups which are more-or-less depending on the vendor were poor man snapshot dedupe features. Why it so? Because the only way Windows 2012 with Hyper-V role can give you a backup is through the VSS framework which could only make a VSS-consistent snap of a VHD/VHDX.The other really ugly method called "Microsoft Incremental Backup" which requires to run VHDX all the time with a snapshot attached which is consolidated during every "incremental" backup.
Long story short, with no proper support from the hypervisor, incremental backups of Hyper-V are good from Hyper-V 2016 onwards, in 2012 any solution is a bit of a kludge and may have issues, BUE included