Kind of a pain to find but it's essentially
`https://www.youtube.com/feeds/videos.xml?channel_id=UCY1kMZp...` and you swap out the channel ID.
To find the channel ID: 1. Visit the creator's page 2. Click on `more` for the full description 3. Scroll down to `Share Channel` 4. Click and copy Channel ID
A bit of a pain but I'm glad I know this now!