Okay, this is not a secret light theme per-se, just a bug where colors get inverted, I have no idea how it happened, it just did, and even tho I think it looks pretty neet, it's quite bright...

I had to force reboot the watch (after 144 days of uptime... damn...) to get it fixed.

It is a known issue, and the next version of Infinitime should fix it, it seems (https://github.com/InfiniTimeOrg/InfiniTime/pull/2046)