Hi there BogdanYarovoy,
Thank you for using Apple Support Communities!
It sounds as though in an app you’re not able to dismiss the keyboard after entering information. You’re in the right place, we’d be glad to assist in seeking a solution.
If there is a “Done” or “Return” key in the bottom right corner this can sometimes work to dismiss the keyboard.
Also, try closing the app and opening it again:
How to force an app to close on your iPhone, iPad, or iPod touch
If you need further assistance, we’d advise reaching out to the app developer. Below is a resource that can help with contacting the app developer:
How to contact an app developer
We hope this helps,
Cheers!