There are 'Blank Blocks' in my kali terminal. It usually happens in links. I'm not sure if it's an issue with fonts but I did try changing it. I tried to google it but I couldn't find anything relevant. I'm not sure if the issue is with kali or the VM.
I hope these screenshots help. Let me know if you know why it's happening.
I'm using Kali VM in VirtualBox on Ubuntu.