Tooltips are hanging and are not being cleaned up when the mouse exits the component viewport.
I’m using Gantt.getGanttInstance() for each instance. When I reopen a view multiple times (and thus creating new instances) I can build up multiple hanging tooltips.

Hello @Octorilla ,
Thank you for the provided details. We are aware of the issue with tooltips hanging when the mouse is quickly moved outside the Gantt container. The dev team will fix the bug in the future. However, I am unable to give you any ETA for the fix at this time.
As a workaround, you can check the mouse position and manually hide the tooltip by using the gantt.ext.tooltips.tooltip.hide method.
Here’s an example of this workaround: DHTMLX Snippet Tool.
Regarding this:
I’m using Gantt.getGanttInstance() for each instance. When I reopen a view multiple times (and thus creating new instances), I can build up multiple hanging tooltips.
You need to destroy the Gantt instance when you create a new Gantt instance: Multiple Charts on a Page Gantt Docs.
Best regards,
Valeria Ivashkevich
DHTMLX Support Engineer