Us developers as a group seem to hold the belief that updating the copyright dates manually is bad or wrong.
But AIUI, the copyright should be more than a simple "today.getYear()" call. If you first published the page in 2020, then the copyright should reflect that.
If instead, when we delete the 2020 and auto update it to _currentYear_ dynamically, we have removed the claim to have published it earlier. So if there is a copyright issue where another site copied some content but left the copyright year as say 2021, now from a first glance it would have the more senior copyright claim.
What you would want is something that generates a copyright notice like "Copyright 2020-2023". See here for more examples: https://www.websitepolicies.com/blog/copyright-notice