Inquiry about possible overwriting of functions.php file

Dear Support Team,
A few days ago, I made some custom modifications to the functions.php file of the theme. However, I’ve noticed that these changes seem to have disappeared.
I would like to ask if it’s possible that the file was automatically overwritten due to a theme update or any other theme-related operation.
Could you please clarify:
whether the latest version of the theme included changes to the functions.php file;
if future updates are expected to overwrite this file;
and whether you recommend using a child theme to avoid this kind of issue?
Thank you in advance for your assistance. I look forward to your reply.

Best regards,
Gianluca