I just realized that on macOS the Preview's text color for thread names and design details doesn't comply to Dark Mode: It stays black and is quite difficult to read. Such a dumb mistake (especially as the thread list title is correctly displayed) and easy to fix: Another small correction for the next minor release…
Funny enough: Either nobody is using StitchBuddy's Preview in Dark Mode, or this issue isn't significant enough for being reported 😉