I’ve tried uploading different sizes, file types, resolution as well as adding custom code to functions.php file and custom css. Also the thumbnail regenerate plugin.
It appears that our team element image preset sizes are intended for smaller blocks. On our screens, the images were not as blurry, as the images were larger than the render size.
If you want to add larger images, the fastest way to achieve this would be to use an image block above the team block.