I'm not sure if you're still tracking this question, but I'd like to help. It's been awhile since I've dove into the guts of zsh's completion system, so this will be a good excuse.
For now, we'll use this answer as an ongoing tool for me to provide useful tidbits to help you (and I) troubleshoot the problem.
As you can tell, zsh's completion system is very powerful. Sometimes, it completes items that you don't want completed. For example, you almost always want to limit arguments to the 'cd' command to be directories. HOWEVER, in zsh, those could be filesystem directories, named directories, directories in various path variables, or even directories stored in standard shell variables. So, I think the first step is to determine the "context" of your completion.
Please cd into the my_folder directory above, and then type:
CTRL-Xh is the default key combo to display the current context for completion. Please let me know what the output from this key combo is. For example, my output looked like this:
tags in context :completion::complete:cd::
local-directories (_alternative _cd (eval))
The key item to notice is 'local-directories'. What we DON'T see here is a commonly-occurring item 'path-directories', which refers to directories that can be found in $cdpath, and possibly other locations. (I can't remember offhand.)
If you see items other than 'local-directories', that will be a hint as to where this rogue 'proxy' entry might be coming from. For example, here are the types of items my zsh setup will try to complete if I attempt completion from the beginning of the command-line without typing anything:
commands builtins functions aliases suffix-aliases reserved-words jobs parameters
You may indeed see one or more of those items with your CTRL-Xh output, or even items I don't list above. (Those are just examples)
Here is a way you might be able to help limit zsh to only providing local directories and $cdpath directories as completion options:
zstyle ':completion:*:cd:*' tag-order local-directories path-directories
If you don't want some moderately-useful cd magic that zsh offers, drop the 'path-directories' from the end, and I believe you'll get the behavior you want. You'll want to put this into your .zshrc file to make it persistent across sessions. Let me know if this helps.