Hari is this a mandatory update?
No, it's just the JS files of that extension will be lighter. So it's worth it if you care about your website weight.
Webpack v5 support was added in Flarum 1.2, so I updated all my extensions.
2.5 KB -> 1.84 KB
It's not much, but if you have a lot of forum extensions and they would all update Webpack, that would be a few tens of kilobytes of savings.