Dear Aliona,
Each submission in the results file starts with these lines:
# Results on Friday February 26 2021 14:31:11 UTC # USER AGENT: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:85.0) Gecko/20100101 Firefox/85.0
As you can see, in this case, the submission came from a participant (me) who used Firefox. This is not 100% reliable, but there is no method that is 100% reliable when it comes to determining the browser’s identity
Jeremy