Dayjs doesn't support DST. There's a GitHub issue regarding this, which has been opened since 2020: https://github.com/iamkun/dayjs/issues/1271.

I migrated my app to use Luxon because DST is important for us. Check out the timezones docs for Luxon here: https://github.com/moment/luxon/blob/master/docs/zones.md

Side note: there's a noticeable difference in bundle size between the two libraries. I'm using Luxon on server-side so bundle size is not as important as it is on client-side. You might as well check other options for date libraries (date-fns, moment.js) but first check if they support DST.