Here is a letter of Sri Aurobindo himself explaining this in response to a similar question.
‘In some of the Mother’s prayers which are addressed to “divin Maître” I find the words: “avec notre divine Mère”. How can the Mother and “divin Maître” have a “divine Mère”? It is as if the Mother was not the “divine Mère” and there was some other Mother, and the “divin Maître” was not the Transcendent and had also a “divine Mère”! Or is it that all these are addressed to something impersonal?
The Prayers are mostly written in an identification with the earth-consciousness. It is the Mother in the lower nature addressing the Mother in the higher nature, the Mother herself carrying on the sadhana of the earth-consciousness for the transformation praying to herself above from whom the forces of transformation come. This continues till the identification of the earth-consciousness and the higher consciousness is effected. The word “notre” is general, I believe, referring to all born into the earth-consciousness—it does not mean “the Mother of the ‘Divin Maître’ and myself”. It is the Divine who is always referred to as Divin Maître and Seigneur. There is the Mother who is carrying on the sadhana and the Divine Mother, both being one but in different poises, and both turn to the Seigneur or Divine Master. This kind of prayer from the Divine to the Divine you will find also in the Ramayan and the Mahabharat.’
21 August 1936
(Ref. https://incarnateword.in/cwsa/32/general-comments-on-the-mothers-prieres#p4)
The Divine, when He descends upon earth, does not come to do sudden dazzling miracles. His or Her main concern is to inspire and help us grow from where we are today to what we can become tomorrow through Sadhana. A dazzling Divine doing miracles from birth, all too high and brilliant beyond measure, will be ideal for worship and asking things, but not awaken hope and aspiration in us to grow into the image of the Divine. She has not come to prove that She is Divine and earn our reverence! She has come instead to inspire us, to transform us, and that is best done when we see that She is like one of us and yet realised what She did. So we too can do so.
Of course She already had the greatest of realisations even before coming to Pondicherry. But in this prayer She is referring to her nature which, by her highest standards, is still too mediocre for the Work She is here to do. She is showing us that even if we are full of limitations, by offering ourselves sincerely to the Divine, all deficiencies can be overcome. Sri Aurobindo has explained this human side of the Divine Avatar in detail in his chapters on the Avatar in Essays on the Gita.
Most importantly, it is the beauty of the Divine that He is most humble. That is why He despises nothing, accepts everything as His very own. It is human beings who suffer from the disease of superiority.
Affectionately
Bhaiya
