The firmware is part of the hailort-pcie-driver_4.18.0_all.deb file. The firmware is loaded by the driver to the Hailo-8 device when the driver is loaded.
You should be able to find the firmware file in /lib/firmware/hailo/
There you may also find a link to other hailo firmware files in your system. I have a link
hailo8_fw.bin -> /etc/alternatives/hailo8_fw.bin
That link should point to the latest firmware file. If it does not, delete the link and create a new one to the 4.18.0 firmware file.