Configuration
JQMIGRATE: Migrate is installed, version 3.3.0 jquery-migrate-3.3.0.min.js: 2: 711
WordPress jQuery: 3.5.1, Migrate: 3.3.0, UI: 1.12.1 plugins.php: 982: 20
Theme: Neve / Neve Child
If jQuery UI 1.12.1 is enabled, Neve's customization options only display Widgets: Layout, Header, Footer ... Additional CSS no longer appear.
At your disposal for any further information, if necessary.