Most likely given this huge hashrate, there is some mega efficient and fast ETH ASIC out there that is being put into production. This is similar to what happened back in 2018 when the hashrate went up so fast that they weren't producing GPUs fast enough to account for the increase. Then 3 months later we learn't of Bitmains ETH ASIC.
Given how there is a chip shortage and given how most GPUs on the planet are mining ETH there is no other explanation for this huge increase in hashrate. Another explanation can be that maybe there is some exploit similar to ASICboost for BTC. Maybe some farm found a way to get more hashrate out of their current GPUs so instead of mining at 30MH/s they maybe mine at 40MH/s with some GPUBoost for ETH. This is purely speculation however there is definately some farm out there which is at a huge advantage because this hashrate increase is unbelievable.
I have read somewhere the ETH developers were getting their hands on ASIC miners. Not sure if this is reliable or not. They have the money to do that if they wanted to. All this talk of a 51% attack probably made them concerned. So they are probably willing to pay to get enough hash rate to make sure this could not happen after they implement EIP 1559.
The guy who first suggested EIP 1559 has an agreement for asics that I think I heard was in place shortly before he suggested it.
I also think that the concerns you stated may be why linzhi never actually publicly sold their miners. They had tapout I think in late 2018 and ordered 38 wafers for that run of machines and never publicly stating how much more they ordered or having talked about new development in their chips.
If a company spends $30m USD they can get around 1,600gh/s likely on ETH of the new Nvidia mining gpu's. This is probably the lower end ones as delivery is fairly quick.
https://www.coindesk.com/hut8-nvidia-mining-gpu-purchaseSupposedly the GPU that runs Nvidia's A100 can do 210 mhs at around 250w. Maybe all the University's and data centers that have these are also mining but still the difficulty has been going up significantly and consistently. With the difficulty the average person has getting a new gpu it's likely most of this now has to be industrial mining.
https://www.pcgamer.com/nvidia-may-be-about-to-launch-a-dollar3000-gpu-that-puts-the-rtx-3090-in-the-shade/This card at $3,000 might be intriguing and begs the question what else does Nvidia have in the pipeline at the $10k range?