Adding text to inside of parenthesis deletes everything after closing parenthesis

Question

When using zsh to write a for loop, if I attempt to add text inside parenthesis (command substitution) after I've finished writing the loop, zsh deletes everything after the last parenthesis. A bit hard to explain, so I've created a screen recording to visualize the issue a bit better.

.zpreztorc, .zshrc, .zprofile, .profile, .zprezto/*, etc. have not been modified from default.

I'm unable to replicate the issue using GNU bash v3.2.57 in the same profile on iTerm2.

zsh --version
zsh 5.7.1 (x86_64-apple-darwin18.2.0)

Running iTerm2 v3.3.0 with shell integration and the Prezto framework for zsh.

I would like to be able to add pipe commands to the end of my command substitution without having to retype the rest of my loop every time.