I for one have an RPi4 running the same kernel (4.19.93) and a Logitech wireless mouse/keyboard which didn't stop working after the update. Here's my output of lsusb listing a "Logitech, Inc. Unifying Receiver":

Bus 002 Device 003: ID 2109:0711 VIA Labs, Inc. 
Bus 002 Device 002: ID 0480:0900 Toshiba America Inc 
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 046d:c534 Logitech, Inc. Unifying Receiver
Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

If you wish to investigate the problem, you should make your test repeatable (and your question much shorter):

• install a vanilla Buster image before the update, verify that the keyboard works
• install a vanilla Buster image after the update, verify that the keyboard stops working
• open SSH access or a serial console on the RPi and compare the output of diagnostic commands (dmesg | grep usb, lsmod and lsusb would be a start) between the two systems. Post those differences.

I for one have an RPi4 running the same kernel (4.19.93) and a Logitech wireless mouse/keyboard which didn't stop working after the update. Here's my output of lsusb listing a "Logitech, Inc. Unifying Receiver":

Bus 002 Device 003: ID 2109:0711 VIA Labs, Inc. 
Bus 002 Device 002: ID 0480:0900 Toshiba America Inc 
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 046d:c534 Logitech, Inc. Unifying Receiver
Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

If you wish to investigate the problem, you should make your test repeatable (and your question much shorter):

• install a vanilla Buster image before the update, verify that the keyboard works
• install a vanilla Buster image after the update, verify that the keyboard stops working
• open SSH access or a serial console on the RPi and compare the output of diagnostic commands (dmesg | grep usb, lsmod and lsusb would be a start) between the two systems. Post those differences.

Considering how widespread Logitech hardware is, I would imagine the problem is specific to your case somehow, else we would be seeing "Rasbian Logitech Mouse/Keyboard issue" headlines all over the place.