Another perspective is this: https://matija.suklje.name/how-and-why-to-properly-write-copyright-statements-in-your-code. Matija suggests to add the year once as the year of file creation, but not change it afterwards.
Thanks, the writings of that lawyer coincide with the text that I found later that mentions Google's lawyers and Netflix's lawyers (https://hynek.me/til/copyright-years/), about not changing copyright years. There, time is finite and must be spent in the most useful tasks.
