Bhishma schools Karna. The old man clearly had a measure of the man https://www.sacred-texts.com/hin/m05/m05169.htm https://twitter.com/pranasutra/status/1247928805529804801

Karna now does an elaborate song-and-dance

The old man now tells him to sit himself down, for he is in the presence of his betters

Karna's ego is bruised and he retreats to his tent, sulking for ten days and does not return until Bhishma is dead. Absolute irresponsibility. If he had so much gratitude towards Duryodhana, it is a small man who would let his ego get the better of his duty.