I use a dark theme for my operating system and web browser, Baserow is the one application I currently use which doesn’t have a native dark theme.
You can track this feature request here: Dark theme (#234) · Issues · Bram Wiepjes / baserow · GitLab
In the meantime, you may enjoy using an extension like Dark Reader. No ads, doesn’t send your data anywhere, and is fully open source.
Hope this helps.
I tried this extension and there’s some issues like the scrollbars blending into the background, thanks I look forward to seeing this implemented.