I received a mail very recently about my solution to problem flipper being same as someone else. This was my second contest on code forces and I was using an online IDE back then. Unfortunately it seems my code was copied but I don't have evidence to prove otherwise and don't know how to proceed. I have switched to VS code since then and didn't have any similar occurrences. I have attached the mail below.

Attention!

Your solution 206537886 for the problem 1833D significantly coincides with solutions SD_drago/206537886, krish0522/206543895. Such a coincidence is a clear rules violation. Note that unintentional leakage is also a violation. For example, do not use ideone.com with the default settings (public access to your code). If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details. More information can be found at http://codeforces.com/blog/entry/8790. Such violation of the rules may be the reason for blocking your account or other penalties. In case of repeated violations, your account may be blocked.

It seems I have not lost any rating but would like to take further steps in order to avoid this happening in future. Thank you for your help/advice.