Thanks for the detailed responses and raising this very important issue.
You are right - there is an issue. Looks like indeed Kernel update caused compatibility in our driver version 5.3 - However please note that officially only version 5.1.1 is supported on Pi - the one that comes from sudo apt install hailo-h10-all: https://www.raspberrypi.com/documentation/computers/ai.html
and for that version del_timer_sync is not used.
Thanks,