Thanks for the super fast response! (going back to 4.3.0 solved the problem)
heard back from support, you can download previous versions at https://github.com/udx/wp-stateless/tags (going back to 4.3.0 solved the problem)
After upgrading I have a critical error on my site related to the length of a firebase token. After disabling the plugin everything works. Is it possible to reinstall the previous version?
Thanks!