Where can you get a piece of tubing that is between extrusion block and the heat block?
What type of material is it? Is it heat treated?
Which printer do you have?
My Creality K2 Plus and K2 Pro do not have such tubing. It goes directly from the extruder to the nozzle. I assume Creality Hi does the same thing since it uses the very long nozzles. If you heat up the nozzle and then remove it you will see you are looking at the nozzle not any tubing.
So next question you may have is that you see filament when you remove the extruder. Heat the nozzle and use a poke to push it out. If print temp doesn’t allow you to push the filament out, you need a new nozzle.
It is PTFE tubing you can get it on any 3d print supply store, amazon have some interesting post and aliexpress is a jungle of them.
be sure of get the same diameters, internal and external.