They are transferring from pre-segwit to segwit addresses as per OP:s/Murch's thread. Good in theory, but the executed in an expensive and somewhat disruptive way.

I'm 65% sure this was in some way malicious on Binance's part.

shyfire

BlokchainB

"I'm like 95% sure that Binance dumped a shit ton of UTXOs in mempools to just slow the dump down."

bitcoin

Binance's hot mess | MempoolReport, by Murch 

cointastical

> "I'm like 95% sure that Binance dumped a shit ton of UTXOs in mempools to just slow the dump down."

https://www.youtube.com/watch?v=KjlWpLHtEUs&t=421