I have just configured this repo to use coveralls actions as a coverage badge, created the secret as in the image below:

And as you can see in here, I am using the correct secret.
However, everytime I run this job I get the response Bad response: 422 {"message":"Couldn't find a repository matching this job.","error":true}
I have no idea what to do. I already checked in the coveralls website and the repo is fine... I noticed that github secrets page updated, and neither Coveralls nor Github documentation updated as well, the Coveralls docs is actually useless, it does not help in nothing regarding github.
Just wanted to mention that your fix was correct because, of all Coveralls integrations, the Coveralls Github Action is the only one that uses a token other than the Coveralls Repo Token to identify the repo to the Coveralls API. Since
${{ secrets.GITHUB_TOKEN }}is available from the Action itself, it is meant to be a faster, more convenient way to configure your integration with Coveralls.As it may help, some more information on Coveralls integrations:
v2.0of each): the Coveralls Github Action & the Coveralls Orb for CircleCI.