HTTP/2 is the latest update to the HTTP protocol. It’s a refresh of the original that is more efficient in speed and security. Some of the major improvements in the HTTP/2 is single connection, where only one connection to the server is used to load a site and that connection stays open until exiting out of the website. Another example of an improvement in HTTP/2 is multiplexing. This means that multiple requests are allowed at the same time on the same connection. This is a big improvement since before, with the original HTTP version, you would have to wait for other transfers to be complete. HTTP/2 have many other enhancements including the increase in connection speed which is great for mobile users and overall for a better user experience.
With Googlebot supporting HTTP/2, websites that support the protocol will most likely see an increase in rankings due to the boost in speed. Slow websites affect conversions and causes users to leave a website. Studies show that by having a faster site speed will lead to increased sales and conversion rates, making HTTP/2 ideal to implement on your website. In conclusion, there is no downfall to upgrading to HTTP/2 because if a user can’t load the site over HTTP/2, the site will load just like it always has.