Backspace Misbehavior in PyCharm Terminal When Pisces Plugin Is Active

Summary: 
When using the Pisces plugin in Fish shell inside PyCharm’s integrated terminal (WSL Debian), pressing Backspace replaces characters with = and causes erratic cursor behavior. Removing Pisces resolves the issue. Other terminals (Windows Terminal, VSCode) do not exhibit this behavior. 
I think this issue is present even in Windows without WSL. 