Elevate Ubuntu 20.04: Key is stored in legacy trusted.gpg keyring

Symptoms

Attempting to elevate returns the following errors.

All packages are up to date.
W: https://wp-toolkit.plesk.com/cPanel/Ubuntu-20.04-x86_64/6.6.4/wp-toolkit/./InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.
W: https://wp-toolkit.plesk.com/cPanel/Ubuntu-20.04-x86_64/6.6.4/thirdparty/./InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.
W: mirror://httpupdate.cpanel.net/ea4-u20-mirrorlist/./InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.
W: mirror://httpupdate.cpanel.net/cpanel-plugins-u20-mirrorlist/./InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.

Description

Ubuntu has deprecated the use of the legacy keyring, which causes deprecated messages to appear during apt updates. Errors during system updates can cause Elevate to stop processing the system upgrade. This issue is likely to occur in older systems but not newer systems.

We've opened an internal case for our development team to investigate this further. For reference, the case number is CPANEL-46455. Follow this article to receive an email notification when a solution is published in the product. 

Workaround

Export the legacy keys.

apt-key export D9170F80 |gpg --dearmour -o /etc/apt/trusted.gpg.d/wptk.gpg

apt-key export 7E931C7C |gpg --dearmour -o /etc/apt/trusted.gpg.d/cpanel_plugins.gpg