The preview feature may not be available for some websites, such as Twitter, due to technical or security reasons. To access the preview feature, you may need to add either "fx" or "vx" to the domain name, i.e. fxtwitter or vxtwitter. This will allow you to view a preview of the website before visiting it, which can be helpful if you're not sure what content is on the website. Additionally, adding either "fx" or "vx" to the domain name may help to improve your security by allowing you to preview the website and determine if it is safe to visit.
