WordPress post using block editor displays error when adding the string "cmd.exe"

Today a member of our content team reported that when they attempted to save a post in block editor mode, they continually received an error.

Updating failed. The response is not a valid JSON response.

After some debugging steps we determined that the string cmd.exe was to blame. When that string was present the author always got the above error. But when the string was gone or had a space after the ., the post saved and displayed just fine. I recreated it in a brand new post, with only the string cmd.exe and confirmed that I got the same error.

When viewing the post in the code editor view, this is the contents:

!-- wp:paragraph --
pcmd.exe/p
!-- /wp:paragraph --

We're currently running WP 5.7.2 on WP Engine.

Does anyone know why this might be happening? I understand it's probably a security issue, but this seems quite the ham-fisted approach.