Redirect to URL, will redirect the new response once the quota has been reached.  If you want to know the reason/ you need to flag the responses in Data and Analysis, you can update an embedded data in the survey flow with the branch logic based on the quota, right after the quota question.

The redirection is ok, but for one target i put 20 but i have 30 responses for example.

i was thinking when the quota has been reached, it will stop the interview like i said on the options.

but for a reason i don’t know the quota have been exceeded.

 You need to change the settings, “Prevent all new survey session”.  This will restrict the new responses falling in to the exceeded quota.