Theophylact of Ohrid

But after the coming of Antichrist, the frame of the world shall be altered and changed, for the stars shall be obscured on account of the abundance of the brightness of Christ. Wherefore it goes on: But in those days, after that tribulation, the sun shall be darkened, and the moon shall not give her light; and the stars of heaven shall fall. That is, the Angelic virtues shall be astonished, seeing that such great things are done, and that their fellow-servants are judged.

Catena Aurea by Aquinas ↗

Ambrose of Milan

And just as when the moon is in opposition to the sun, it disappears through the regular flow of the menstrual cycle or through the alignment of the earth, so too the holy Church, when the vices of the flesh oppose the heavenly light, cannot receive the divine radiance of Christ's rays. For in persecutions, the love of this life often excludes the light of God alone. …

Commentary on Luke, Book 10 ↗

Gregory the Dialogist

Our Lord and Redeemer, most beloved brethren, desiring to find us prepared, announces what evils will follow upon the aging world, so that He might restrain us from love of it. He makes known what great calamities will precede its approaching end, so that if we are unwilling to fear God in times of peace, we may at least fear His judgment drawing near, worn down by these afflictions. Of all these things, we certainly see some already accomplished, and we dread others as soon to come. …

Forty Gospel Homilies, Homily 1 ↗

Bede

For the stars in the day of judgment shall appear obscure, not by any lessening of their own light, but because of the brightness of the true light, that is, of the most high Judge coming upon them; although there is nothing to prevent its being taken to mean, that the sun and moon with all the other heavenly bodies then for a time are really to lose their light, just as we are told was the case with the sun at the time of our Lord's Passion. …

Catena Aurea by Aquinas ↗