I'll start by stating that I don't know if this is pure PHP or a framework. - I don't know anything about it (but a real programmer can handle anything).
The problem with the referral link is that it doesn't assign a referrer or display the source of the link click.
Overwriting the files doesn't help.
Same with changing php version.
And installing the script from scratch link works fine.
I'll give the website address to those interested, so they can trace the script in the developers console.
I do not want to reinstall the script because I have a few users. And I'm afraid that after some time the error may occur again.