Re: ~80 MB transactions with 1 s/b fee were just injected into the mempool
someone (a service or maybe a spammer?) created about 3000 transactions with about 80 MB in size (in total) and flooded the network with them:
image source: https://statoshi.info/dashboard/db/memory-pool
image source: https://statoshi.info/dashboard/db/memory-pool
That usually means either a pump or dump is incoming for the bitcoin price.
If you clog the mempool, people can't get their coins to the exchanges to sell, which makes a pump easier as it is only dealing with coins that are already on the exchanges. Once people do get their coins on the exchange you get the dump phase where all those coins are suddenly dumped on the exchanges causing the price to tank.