Horde support will be removed from cPanel & WHM starting with Version 108. This is because Horde does not support PHP 8.x, and PHP 7.4 reaches End of Life in November 2022.

What does this mean for clients that use Horde?
Our Webmail offering will be focused on Roundcube going forward. Your email will be available in Roundcube just as it is in Horde today.

What do I need to do to prepare for this?
Nothing currently.

What about my calendars and contacts?
cPanel will be providing migration tools that will help Horde users move to Roundcube. We will have more information on those at a later date.

More information from cPanel here