The funny thing is that in 0.79 I played against a TEC Rebel Unfair AI which actually spammed massive fleets at me. I also noticed that the Advent are becoming nearly unbeatable in late stages of the game on huge maps. In one battle I fought an Advent fleet that whas composed of a Titan and 8 Capital ships, while my own fleet counted 14 capital ships and a Titan of my own. Due to the Advents extremely high shield mitigation levels (a level 10 Radiance Battleship even had 79% shield mitigation and 20 Armor!
) I ended up victorious after having lost all but three capital ships and nearly my entire supporting fleet. It was a tough battle.
To return to the OP: I have also noticed that the AI seems to be using even less frigates than usual. Definitely something that needs to be adjusted, preferably before the next patch is released.