On the Manage Course and categories screen with Tiny as the text editor, when adding a new category the Search list for the parent category is layered behind the Description text field. This happens for both the Clean and Boost themes in Chrome and Firefox at least.

It does not happen with Atto or plain text editors and is still an issue in the current build (20230916) of 4.3.

Setting the z-index of .form-autocomplete-suggestions to 3 (up from 2 in the current CSS) seems to fix the problem in this instance, although this may not be the only place where a drop down might be layered under the Tiny text editor.