Timeless Timing Attacks (TTAs) leverages multiplexing of network protocols and concurrent execution by applications, thus making the attacks immune to network conditions. Attack can also be deployed against Tor onion services, such as those that only support HTTP/1.1, allowing an attacker to create two Tor connections to a particular Tor onion service and then simultaneously send a request on each of the connections to measure a timing difference of 1..s. The findings will be presented at the USEN Security Symposium later this year.
Source: https://thehackernews.com/2020/07/http2-timing-side-channel-attacks.html