I'm making a chrome extension and I want to change the tab's css, but I get this error:

Uncaught TypeError: Cannot read properties of undefined (reading 'insertCSS')

Here is my script:

applybtn.addEventListener('click', function () {
    chrome.scripting.insertCSS({
        target: { tabId: activeTab.id },
        files: ["/src/themes/test.css"]
    });
});