Config wrong domain
Check your website config URL in the file app.dart
https://appcheap.io/ => https://www.appcheap.io/
Or
https://www.appcheap.io/ => https://appcheap.io/
You can find correct the URL in your admin dashboard Settings => General
The Authorization header is not working
You can check here Admin dashboard => Tools => Site Health => Info (tab)
Conflict plugins
You can disable plugin list below and check the app again.
- YaySMTP – Simple WP SMTP Mail
- JWT Authentication for WP REST API