Here is how we fixed this issue with javascript:
function onTidioChatApiReadyChangeZIndex() {
(function() {
const tidioChatIframe = document.getElementById('tidio-chat-iframe');
if (tidioChatIframe) {
tidioChatIframe.style.zIndex = '4000';
}
})();
}
if (window.tidioChatApi) {
window.tidioChatApi.on("ready", onTidioChatApiReadyChangeZIndex);
} else {
document.addEventListener("tidioChat-ready", onTidioChatApiReadyChangeZIndex);
}