If you're wanting to discuss a particular year, you might have noticed that number-only hashtags don't work on here.
To get round this, a lot of people use the word "year" before the number, for example #Year2024 or #Year2025
(By the way, there is a discussion about this issue on Mastodon's Github page at https://github.com/mastodon/mastodon/issues/9709)