A small maintenance release, as is customary after a major release, to resolve a few problems encountered since then.
The next major release (2.27) is scheduled for mid-August, which will also be the occasion to celebrate Dotclear's 20th anniversary, and you should know that this version will be the last to still support PHP 7.4.
Starting with 2.28, which will be released at the end of the year (mid-November a priori), you'll need at least PHP 8.1 to run.
You can already prepare for this by switching to this version, or even better to 8.2, as Dotclear has been supporting it well for several versions now!