Accessibility error?

When testing my frontpage I get the following message from https://web.dev that test for ARIA elements being correct:

ARIA tooltip elements do not have accessible names.
When an element doesn't have an accessible name, screen readers announce it with a generic name, making it unusable for users who rely on screen readers. Learn more.
Failing Elements
div
<div id="tt" role="tooltip" class="cmtt">

I am assuming that this is a tooltip html tag? Something you can have a look at?

The page I need help with: [log in to see the link]