Microsoft is working on resolving a high-pitched noise issue Windows 10 users hear when using some 5.1 audio configurations after applying recently released cumulative updates. The issue only affects Windows 10, version 20H2 and Windows 10 version 2004 client platforms. Microsoft also removed the last remaining compatibility holds, blocking customers from upgrading to Windows 10 2004 and 20 H2 after fixing Conexant and Synaptics audio driver issues, causing errors and problems while updating. Microsoft customers have also had to deal with audio ‘difficulties’ in the past, with Windows 10 audio problems affecting gamers in September 2019.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-investigating-new-windows-10-high-pitched-noise-issue/