Zero-width characters embedded in phone number whenever they are copied from the macOS address book
update 11/2020: It seems like this may be finally fixed in macOS 11. When I just tried it, copying a phone number using the normal ⌘command + C did not add the extra gremlins. Can anyone else confirm?

This isn't an answer but I wanted to add a screenshot as some people have requested it.
I noticed this bug as well (as recently as 10.15.7) and was glad to find this already reported, and surprised it hasn't received more attention.
I filed bugs #47763641 &amp; #5235503 with Apple, hopefully they will notice. I encourage others to report it.
Here are steps to repro &amp; a screenshot that shows the issue:

From Contacts.app, right-click → Copy on a phone number.
Paste into Sublime Text or any other plaintext editor.
Save as test.txt
Open in a Hex Editor, I used Hex Fiend in this example
You can now see the extra bytes (I highlighted them below)


a couple of bits of information:

This seems to only affect phone# fields. Others such as email, addresses, notes etc don't exhibit this bug.
If, instead of using ⌘command + A (select-all), you very carefully select just from the start of the phone# to the end and then copy, the unwanted zwsp characters aren't copied.

My workaround for now is an Alfred workflow that I mapped to ⌘⇧C that copies the selected field and trims the whitespace. Not exactly elegant, but it works well enough until Apple fixes this (which they may have as of 11.0)