With version 5.8, WordPress Core has taken another step towards Full Site Editing and converted the previous widget areas into block areas. Under Appearance → Widgets and in the Customizer, a new block-based Widget Editor has been introduced for this purpose, with which blocks can now be inserted into any widget area.
For the new block-based widgets, we have also made some adjustments in our themes and Pro add-ons. These updates have been released the last few weeks.