Gabriel Lafreniere - Thanks for the question and using MS Q&A Platform.
As of now, dark mode theme for Synapse Studio is not yet available.
Currently, we don't have any ETA when it will be available. I hope this feature will be available soon in synapse studio and I will update this thread once it’s available.
Note: Last month the dark mode theme for ADF studio is released and the product team is working for the same in Synapse studio.
Appreciate if you could share the feedback on our feedback channel. Which would be open for the user community to upvote & comment on. This allows our product teams to effectively prioritize your request against our existing feature backlog and gives insight into the potential impact of implementing the suggested feature.
Hope this helps. Do let us know if you any further queries.