Regexp for displayname does not match with what's in my profile

[SylvainGarnier]

no backslashes before doublequotes and digits in the displayname value

ex:
,"displayName":"36e29d65-715c-456b-9115-84f0b9a0c0ba","

Worked for me with this edit in the script: (line 326)
PATTERN = re.compile(
r"."displayName":"([-.\w\d]+)".", re.MULTILINE | re.DOTALL
)

Not sure if this is due to a Garmin API change or a particular case on my account setup (did not find how to change this display name in my account)

[pe-st]

There is an open pull request in this repo that might already fix your issue: #30

And I added your example as test case in my fork of the script, where the display name is correctly extracted (a couple of months ago my fork already had to be adapted to the changed HTML from Garmin)