Replace the pullup resistors at SDA and SCL between the MUX and the buffer to 4k7 or 10k.
Remove all the capacitors at SDA and SCL between the MUX and the buffer.
Replace all pullup resistors for the cable with more reasonable values. Perhaps 470Ω or 1k.
A twisted pair signal would be better. That is a twisted pair for SDA and a twisted pair for SCL: https://hackaday.com/2017/02/08/taking-the-leap-off-board-an-introduction-to-i2c-over-long-wires/