What is the depth of the "insights" analysis?

How much depth play levels?

Or what's meant by the word depth? 

Depth means how many half-moves (ply). So depth 18 would be 9 mines deep in an analyzed line.

That information hasn't been released anywhere.

It's not public information, but I was able to figure it out. (TL;DR: it's depth 22)

I checked my insights specifically for Blitz, and chess.com said I played three brilliant moves on March 6th, 2023.

After analyzing every blitz game I played on March 6th, I was able to find not three, but four brilliant moves. For anyone that would like to verify, since this was the basis of figuring out the depth used for insights, they're in the games against elijah_ash, willgrayed, igorDyrda (first game, black pieces) and nimish942.

Immediately I realized that there must be a discrepancy between the depth that awarded me a brilliant move and the one used for insights. I analyzed all four games on depth 18, 20, 22, 24, and 26. Every single analysis gave me a brilliant move, except for specifically depth 22 against willgrayed.

Strangely, depth 18, 20, 24, and 26 still consider the move brilliant. I'm not sure how the engine can realize a move is brilliant, change its mind after further consideration, and then change its mind again after even further consideration.

In any case, it is extremely likely that depth 22 is the depth used for insights, unless the actual depth is lower than 18. It's extremely unlikely that chess.com would choose to use a depth higher than 26 to analyze thousands of games from users on-demand with such a time-consuming depth.

TL;DR: chess.com uses Depth 22 for insights.