Another thing I could add about Diaz might have been the circumstances happening in that period of time.
When he joined Liverpool we then won the FA cup and 2 Carabao cups. Negotiating time occurs for an extension at some point, the owners play it really hard ball, we will give you less until you give more. e.g we’re interested in League and European titles.
He’s already arranged his move in advance to Bayern way before Liverpool are gonna be crowned champions.
Tough luck and an exceptional attacking player gone that should have had more encouragement to resign.