Undefined array background_video warning when placing a block

A patch has been added to fix this issue.

Also here I am running into this issue. making it impossible to update layouts as all added sections are 'saved'.
After applying the patch, still the same issue. Adaptations are saved according to front end, but on re-opening the layout, the newly added sections disappeared.

After applying the patch, I am getting a OutOfBoundsException: Invalid delta "0" in Drupal\layout_builder\Field\LayoutSectionItemList->getSection() (line 42 of ***/public_html/core/modules/layout_builder/src/SectionListTrait.php).

Probably this issue is obsolete since 🐛 InvalidArgumentException: Invalid ID provided for the "media" entity Active already changed same lines as patch from #2. Can anyone provide steps to reproduce this issue?