Check and found: Addon: Modal Popup conflicts with other form plug-ins, I don't understand why this pop-up Modal Popup has this problem, but I can't disable other plug-ins, there is no way, I can only temporarily remove it.

If any of you are testing, please help me fix it, there is a Modal Popup on the About Us module on the home page that cannot be used

Hello isemc

There is no alternative way, unfortunately. You have to disable the plugin or use other addons. You can try Raw HTML addon and create the modal popup.

Best regards