Flop Analysis
Flop Qh2c6h gives us an overpair on a semi-wet board with SPR ~3.5. Solver mixes between small c-bet, medium c-bet, and check; checking here is reasonable, especially if BB defends wide and continues with a lot of Qx and draws.
KK on Qh2c6h4sQc is strong but not invincible; a small or medium river bet is preferred over a large one.
Flop Qh2c6h gives us an overpair on a semi-wet board with SPR ~3.5. Solver mixes between small c-bet, medium c-bet, and check; checking here is reasonable, especially if BB defends wide and continues with a lot of Qx and draws.
Turn 4s is a brick and BB checks again. We still have a strong overpair and checking back is fine—our range is already strong and we don’t need to build a huge pot. Betting would mostly get called by Qx and better, while worse hands often fold.
River Qc pairs the board and SPR is still ~3.5; with KK we have a strong but not invincible hand. Solver likes a small or medium bet here, but also has a chunk of checking. The 6.5BB bet is a bit too big for a small pot and doesn’t meaningfully change the EV compared to a smaller bet.
Note: River bet size is unnecessarily large; a small or medium bet captures value from Qx and weaker pairs without risking more than needed.