One verse

Srimad Bhagavatam 8.21.10

8.21.10

न वायं ब्रह्मबन्धुर्विष्णुर्मायाविनां वर: । द्विजरूपप्रतिच्छन्नो देवकार्यं चिकीर्षति ॥ १० ॥

na vayam brahma-bandhur visnur mayavinam varah dvija-rupa-praticchanno deva-karyam cikirsati

na
not
va
either
ayam
this
brahma-bandhuh
Vamanadeva, in the form of a brahmana
visnuh
He is Lord Visnu Himself
mayavinam
of all cheaters
varah
the greatest
dvija-rupa
by assuming the form of a brahmana
praticchannah
is disguised for the purpose of cheating
deva-karyam
the interest of the demigods
cikirsati
He is trying for.

This Vamana is certainly not a brahmana but the best of cheaters, Lord Visnu. Assuming the form of a brahmana, He has covered His own form, and thus He is working for the interests of the demigods.