As I said, I've already tried this instruction, but once I was in restore mode, my mac stopped recognizing my iPad. I don't get any restore options on my computer. Additionaly after I leave the restore mode my computer still doesn't recognize my iPad which is pretty sad. Also, my iPad is now stuck on apple logo so I'm really hopeless now.

Okay, I've managed to boot my iPad into DFU mode, my mac recognized the device and let me restore it with latest public iPadOS and now everything's fine.