pull from heroku gets empty git but there's an online site [duplicate]

Question

Trying to retrieve old code for updating...

heroku git:clone -a appname 

creates empty dir...

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So:

$ git clone https://git.heroku.com/appname.git
Cloning into 'appname'...
warning: You appear to have cloned an empty repository.

$ git remote -v
heroku  https://git.heroku.com/appname.git (fetch)
heroku  https://git.heroku.com/appname.git (push)

$  git pull https://git.heroku.com/appname.git heroku
fatal: couldn't find remote ref heroku

git pull https://git.heroku.com/appname.git
fatal: couldn't find remote ref HEAD

login via heroku bash and "ls -la" i can check there is no .git folder in my app but it works online and i should have pushed it tru heroku cli as theres no other way ( i dont use public github).

It's a django app.

Also tried without understanding well an answer i found:

git fetch -vv --all
Fetching heroku
Fetching here
fatal: couldn't find remote ref refs/heads/heroku
error: could not fetch here

git reset --hard HEAD

which just resets a commit i had locally without fetching remote git

 git remote set-head heroku -a
error: Cannot determine remote HEAD

remote update silent goes on

$ git remote update
Fetching heroku
$

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*App was in maintenance mode, which shouldnt affect but tried by enabling it and do everything again

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edit: i'm diving into this which might or not have been the case heroku help for cloned empty link

heroku git:remote -a appname

it does set remote but i don't have the correct name of the app template used in case it was tru button deploy, which i don't know, but i doubt was the case. So it's not the same case as Heroku "cloned an empty repository" message for a repository that isn't empty

**edit2: this solution by heroku just retrieves the original template, but not the changes that you would have developed further from it

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It probably could only be resolved with the heroku support which im waiting answer.

Or with this hack to retrieve the files https://code-examples.net/es/q/1478abd