After 20 rounds (4 RR) the crossable is:
Komodo was on fire this RR with a result of 4.5/5. Only Stockfish could get a draw against it.
Protector-Hannibal managed to find a draw faster than the reverse game, this time in 19 moves. Protector also had two wins in the fourth RR, after only one in the first 3 RR (not counting the game against Stockfish which was lost). The first win was against Houdini after a long shuffling match. The second win was against Gull with the assistance of the king's gambit opening.
Hannibal held for 30 moves against Komodo, but blundered in the end to allow Komodo to reach a won rook ending.
Stockfish managed to get a draw out of its hard opening against Gull.
Komodo-Gull, round 16
Game on TCEC archive
The opening favoured white but nothing Gull couldn't handle, right? On move 22 the position was:
This was a serious mistake because Komodo used a bishop and knight on both sides of the board to trap Gull's king in the center and freeze the queen side entirely:
The evals show the reality of the position. After exchanging the rook and queen the combination of a passed f-pawn and all the black pawns on white squares ensures the win for white.