• Check if updating to the latest Preact version resolves the issue

Describe the bug
It seems impossible to toggle between having a role attribute (dialog for example) and removing the attribute. For example, I want to have a role="dialog" when a menu is open, but remove the role attribute when it is closed. It currently returns an empty value. This affects accessibility because having an empty role is not valid HTML. You can check that using an HTML validator:

This seems to be the behavior in Preact with the following options:

• Using null: It keeps the role attribute in the element.
• Using an empty string: It keeps the role attribute in the element.
• Using false: It sets role="false".

I also tried using another role value as none, but it changes the accessibility tree.

I made a quick video using this CodeSandbox explaining that better:

I've tested it in React, and it seems possible to remove the role attribute by using null. I used this other CodeSandbox as shown in this other video:

To Reproduce

Preact behavior

Using this CodeSandbox, toggle between the different options to see how the role attribute of the div containing the <pre> element changes.

React behavior

Using this CodeSandbox, toggle between the different options to see how the role attribute of the div containing the <pre> element changes.

Expected behavior
It should be possible to remove the role attribute as it happens in React.