i don't know what's causing them but you think monkeys? 
Haha no. It is 99.9% BRC20 inscriptions. The real entity to blame now is Binance since they started listing $ORDI token.
What is Binance getting from listing a BRC-20 pseudo-token? Oh yeah, trading fees.
Well I cannot say I am surprised. This company has done shadier things such as wanting to reverse a block using a 51% attack in order to recover money from one of their hacks.
Binance treats the mempool like it's a giant public restroom.