FullThrottle Labs Flutter Developer interview questions

I applied through LinkedIn. They responded with a form to fill asking current CTC and expected CTC. After filling the form . The HR sent a mail to do an assignment. The assignment was to build a simple app with flutter and send the apk and code in github public repository in One day time. I did the same the assignment within 6 hours ( added more features than they asked.) The next day the HR called and asked the same questions on the form which I filled previously and said they would get back to me after going through the code. After 3 days I sent a follow up mail to which they responded with I was not selected. There was no reason specified. So i would suggest the company to either give a feedback and check the form before giving the assignment. As my guess is my notice period was the problem and not the assignment as I can certainly say they did not even open my app as no entry was entered into the database.