RS232 HAT not working after update to 5.8

I use an older opentherm gateway kit that uses RS232 instead of the newer USB model and to connect that to my home assistant setup i use a RS232 hat that used to give me two extra devices /dev/ttySC0 and /dev/ttySC1.
Since updating to HassOS 5.8 those ports are gone and i have no clue where I should begin looking why this isn’t working.

The schematic for the HAT can be found here but my electrical knowledge is to limited to fully understand what is going: https://github.com/aauer1/RPI-RS232

As far as I can see, there is a chip there that communicates on something called SPI with the PI.
I’m using a Rpi4 4GB model if and my hassos image is 32bit (because the download page said GPIO does not work in 64bit, which seemed important).

Can anyone tell me what to look at to find out why this isn’t working?

Still not working, anybody?