Some Microsoft 365 customers might experience Outlook crashes after updating to Version 2006 Build 13001.20266 and higher. Outlook will also delete three or more emails from their inboxes for accounts configured to retrieve mails from a POP (Post Office Protocol) account with Download Headers Only. Microsoft also said that users will experience one-minute Outlook startups on devices running Windows 10, version 1809 or later if User Experience Virtualization (UE-V) is toggled on. Users who need to work around this issue can revert to a previous version not affected by this problem.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-outlook-crashes-deletes-mails-for-some-pop-accounts/