The graph shows the jump at around 1-2am. That looks like what, 100k-200k votes?
Who was counting? At 10:30 it was announced they stopped counting votes in Fulton county - https://theweek.com/speedreads/947662/georgias-most-populous-county-stopped-counting-ballots-1030-pm
The next morning the GA GOP confirmed that his Fulton County observers were sent home but counting continued:
It has been eating at me all this time because I knew there was a huge dump for Biden.
This post by plushaye at midnight had Trump leading by 340k with 79% reporting. http://freerepublic.com/focus/news/3901227/posts?page=6151#6151
I followed up a few posts later that there were about 300 precincts outstanding, all in Fulton. At 1 am I posted that there were 86 precincts left and Trump was still up 6% http://freerepublic.com/focus/news/3901227/posts?page=6653#6653.
At 1:45am, I posted there were 16 precincts left, 99% in, and Trump had a lead of +2.5. So between 1 and 1:45 am, hours after the GOP observers were sent home, http://freerepublic.com/focus/news/3901227/posts?page=7013#7013
Several posts later I said that that they would literally have to manufacture 120,000 from a few thousand voters. (Little did I know...) http://freerepublic.com/focus/news/3901227/posts?page=7375#7375