Use the classic widgets interface

Use Settings → POM Tweaks → White labelling → Widgets → Classic widgets editor. This control is configured per site, including on multisite, and has moved out of the classic Angular interface.

Follow Configure widgets and menu panels for configuration, discovery, saving, verification, limitations and recovery.

Disable Classic widgets editor and click Save to restore the corresponding native interface, subject to other active controls. Stored widget data and menu items are preserved.