Winning material, then drifting: a common chess weakness

You grab material, then fail to convert it

You win material, then drift and get swindled. Ahead: simplify, trade queens, easy endgame.

• vs rkps0709 (4/21): a rook up by move 12, then drifted, and eventually lost.
• vs AlejoPaez83 (4/1): a huge material lead by move 10, but 40 more moves to win.