What is the standoff between Covid inquiry and Cabinet Office about?

What is the standoff between Covid inquiry and Cabinet Office about? Wrangling over Boris Johnson’s notebooks and WhatsApp messages continues in earnest, with the government and the official Covid inquiry locked in a standoff over what should be shared. The Guardian

See also:

• No 10 denies cover-up over Boris Johnson Covid WhatsApps BBC News
• Ministers dodge Covid inquiry questions on care home deaths until after election The Daily Telegraph
• Former Johnson aide at centre of Covid inquiry battle over private messages The Daily Telegraph
• Sunak accused of trying to cover up ministers’ actions during pandemic The Guardian
• Boris Johnson’s WhatsApp row descends into farce as senior Tories call for Sunak to end dispute The Independent
• The Covid-19 inquiry timeline and what it's hoped it will achieve ITV News
• Prime minister Rishi Sunak says government is 'cooperating with COVID inquiry' Sky News