How did some of the required responses with Google Forms disappear?

Question

Google

I made a Google form and there are 5 mandatory questions in it, you can change the answers.
Received 31 answers, looked at the reports, everyone was in place, in each mandatory question on the answer.
Today I went in and I see that in 1 question there are 12 out of 31 answers left, all other questions are in order.
How could this happen? And how to avoid it?

Answer 1

Check access to the table in which the form adds the answers, all of a sudden it is publicly available for editing, at the same time look at the logs of its change