Zvkg Byte Order

[Nofal475]

I am trying to understand why there is the need for brev8 in Zvkg extension. Explanation given is :

While in the NIST specs for GCM/GMAC(Zvkg) I could only find:

NIST specification for AES demands big endian order. The sail code of Zvkned extension is written in accordance to this, considering inputs are given in big endian. AS GCM/GMAC is used with AES, to make it easy zvkg should take input in big endian. Following this rev8 should be used instead of brev8.

If I am missing some crucial detail please let me know.