There have been many reports about this issue lately:
- https://forums.ageofempires.com/t/after-all-this-time-it-still-drops-a-lot/93225
- https://forums.ageofempires.com/t/are-we-still-in-the-beta-phase/93265
- https://forums.ageofempires.com/t/disconnects-make-the-game-a-frustrating-experience/93199
- https://forums.ageofempires.com/t/disconnects-in-team-games/92820
From my own experience, the chance of at least one player dropping in 4v4 team games is about 50%-65%. It usually occurs in the first few minutes of the game. It is not unusual to have 3 games in a row with at least one player dropping.
As far as I know, there hasn’t been any ‘official’ acknowledgement of the issue and it is not on the Known Issues list, which is quite common for bugs reported on this forum.