This is going to get a little complicated...

You reference fork.lol. They do not measure hashrate directly. They count blocks mined then compute a hashrate. If miners' luck is running below 100%, fork.lol will under-report the hashrate.

The bottom left hand panel here reports some miners' actual hashrates. You'll see that the biggest is currently only running at 75% luck - very unusual. It means the actual hashrate is higher than fork.lol is showing.

Also, BCH had been underblocking, so its difficulty adjusted down to attract miners. It's currently overblocking to catch up - and consequently temporarily taking more haspower than usual.

Put these things together and you're seeing a BCH hash peak that's partly temporary and real, but partly incorrectly reported by fork.lol.

If you look at BCH's actual hashrate here, as opposed to percentage, you'll see it typically runs just over 3 E/s and varies much less than the percentage figure as one would expect given the above.

In a couple of hours BCH's hash share will be back down to around 12%.