CreateToolip() uses a StringBuilder to create the actual tooltip string, which contains some rich text flags (size and color). Now that I know it works with 2022.2.0 I can switch back to 2022.2.1 and see if the PointerDownEvent or rich text has any impact.
I just discovered the exact same problem a few minutes ago. Custom-coded UIElements where I set the tooltip worked in 2022.1 but no longer. No rich text involved, just stuff like:
I am experiencing a similar issue. I have made a custom property drawer using IMGUI, and after upgrading Unity from 2020.3.40f1 to 2022.2.6f1 some of the tooltips have stopped working.
It seems like only the tooltip on the first line drawn stopped working.
They are all made the same way, like this:
EditorGUI.LabelField(fieldRect, new GUIContent(desc.description, desc.longDescription));