Rashi: It is above the Kapores (cover on the Aron); the Shechinah dwelled there until now. It began to depart little by little, in 10 stages - this was the first, from the Keruv to the threshold of Beis Kodshei Kodoshim ¹ .

Radak citing Rosh Hashanah 31a: It says Keruv (singular), for it went from one Keruv to the other, and from the other to the threshold. Perhaps "me'Al ha'Keruv" is a Mashal.

Radak citing Targum Yonasan: It departed like a Keruv that it was dwelling on in the Kodesh ha'Kodoshim. It says ki'Chruva and not mi'Keruva, for it ascended with the Keruv, i.e. the one whom the Keruv resembles - a Saraf, which flies to man. This hints to Nevu'ah departing from Yisrael. Only Chagai, Zecharyah and Malachi remained; they prophesized at the building of Bayis Sheni, and with them Nevu'ah ceased.

Malbim: The Shechinah began to travel from the Bayis. This is a Siman that it will be destroyed.

Malbim: He is the advocate.