ARIA IDs are not all unique
Webflow uses ARIA in some elements, such as TABS and the Hamburger menu. You don't need to do anything, it works fine.
If you get this error, check Custom Code or Element Settings > Custom Attributes.
Google Lighthouse says
Each ID in your HTML document must be unique. Using the same ID on more than one element may cause screen readers and other assistive technologies to only announce the first element with the shared ID, preventing users from accessing the later elements.
Avoiding duplicate IDs is particularly important when using the aria-labelledby attribute. aria-labelledby provides an accessible name for an element by pointing to a second element, using its ID. If more than one element shares that ID, assistive technologies will read the first instance, which may not be what you intended.