What basicly happens every day is that the diff algo forgets the blocks 24h ago from the "instamine" and realizes, shit i dont reach my 1440 blocks per day goal, it then drops the diff until it hits the 70 hardcap, at that point almost everyone can instamine and its a lottery, 70 diff is 6.8 MH total net hashrate.

This stays for a while since blocks coming in and forgetting old ones are roughly at the same speed and after an hour it has caught up, diff for the rest of the day is fucked since we got like 700 blocks in an hour isntead of 60.

Easiest fix would probably to increase the time the diff algo looks back, it should correct itself over time this way but afaik the dev is already on a fix, not sure which one tho.

I guess it all started with the guy(s) who attacked the chain but from there it kept itself alive without any attacks.