OP = Original Poster
Twitch says “stream started at time in UTC of x”
Then your browser goes “get system time and subtract the two”
So if your computer clock is fast/slow by seconds/minutes then it will miscalculate the difference.
It’s “cheaper” to send the start time only (and not Twitch Server time) and let the browser work it out using the system clock than to send two times and math those times.