Hi Pavel_Wei,
If you'd like to look into why you're getting choppy sound from other apps after phone call, these steps might help.
If you want to try more steps on your own
If you prefer, here are some more steps you can try on your own. After following these steps, you might still need to contact Apple Support to discuss service options.
1. Remove all screen protectors, films, or cases from your device.
2. Check the speaker opening to see if it's blocked or dirty. On iPhone only, make sure that the receiver isn't blocked or dirty.
3. If necessary, clean the speaker or receiver opening with a small, soft-bristled brush. Make sure that the brush is clean and dry.
4. Go to Settings > Sounds (or Settings > Sounds & Haptics), and drag the Ringer and Alerts slider back and forth a few times. If you don't hear any sound, or if your speaker button on the Ringer and Alerts slider is dimmed, your speaker might need service.
5. If you hear sound, try making a call with your iPhone and turn on speakerphone. On iPad or iPod touch, make a FaceTime call. If you still can't hear, or hear static or crackling, then your network or reception could be the issue. Try to call again later, or from a different location.
This information is from If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker. These steps will help to eliminate common sources of potential audio interference.
If the issue continues, let the community know the version of iOS are you currently running and if all of your apps are up-to-date.
We hope that helps with your question and take care!