Project management software

Mne nujna pomosh s Microsoft Project.
Hello,
I created the plan and Gant chart, but I have an issue with my stage 2 task. I am getting an error message (please see the screenshots). My stage 2 finish date should be 13/07/2021 (duration 20 days) and Gant chart should represent it (the line now appears longer than 20 days).
Microsoft Project wants to change it to the end date of the project 07/09/2021 (stage 2 and 3 combined).
Can someone who knows PM well can help me to fix this little thing, please?
I cannot attach files (mmp), but I attached the screenshots