We are in moden HTTP/3 UDP era and TFO could be too old technology.
Please check:
Factor 4: Other Performance Improvements
When TFO started out, HTTP/2 was not yet in use – in fact, HTTP/2’s precursor, SPDY, had a draft until 2012. With HTTP/1, a client would make many connections to the same server to make parallel requests. With HTTP/2, clients can make parallel requests over the same TCP connections. Therefore, since it setups up far fewer TCP connections, HTTP/2 benefits much less than HTTP/1 from TFO.
HTTP/3 plans to use UDP (User Datagram Protocol) to reduce connection setup round trips gaining the same performance advantage of TFO but without its problems. UDP is a fundamental Internet protocol like TCP but originally designed for one way connectionless communication. HTTP/3 will build a highly optimized connection establishment system logically analogous to TCP on top of UDP. The end result will be faster than what TCP can do even with TFO.