It might make sense that DiskWarrior 6 has not been released yet, since it requires full APFS documentation disclosure from Apple (Alsoft is under NDA with Apple), and they take time to release new versions (it took seven years to release a 64-bit version of DiskWarrior). APFS for macOS was released on September 2017 (4.5 years ago).
But it does not make sense that they have not released DiskWarrior 5.3 as native for ARM-based Apple Silicon Macs, since it works with HFS+ (not APFS), for which documentation is complete. Even more, on November 2020, Alsoft said that DiskWarrior 5.3 was around the corner and in January 2021 they said that it was in final testing phase. More than a year later we have nothing. Not even a tentative release date. The conclusion seems obvious: key Alsoft Engineers like Rusty Little (Alsoft/DiskWarrior Project Manager) are not probably working at Alsoft any more (coronavirus, underpaid, other?). Otherwise, it just does not make sense, as said.
The bad news is the current situation. The good news is that APFS is much robust than HFS, and that Disk Utility's First Aid can repair APFS disks. Although it would be great to have DiskWarrior 6, of course, just in case. The same can be said for the other disk-repair utilities for Mac: TechTool Pro (Micromat) and Drive Genius (Prosoft Engineering). Time will tell what happens eventually.