In general, if you just want to rotate the tooltips text, just bind the tooltip using a new div for the text:

marker.bindTooltip(
    `<div>${text}</div>`,
    {
        permanent: true,
        direction: 'center',
        className: "markerText"
    }
);

and when rotating the marker, just rotate the text in the div:

marker.setRotationAngle(newAngle);
const tooltip = marker.getTooltip();
if (tooltip) {
    tooltip.setContent(`<div style="transform: rotate(${newAngle}deg); transform-origin: center center;">${text}</div>`);
}