I use sourcetree dynamic mode. (view->appearance->use macOS system appearance)

And I use macOS dynamic mode.

When macOS changes from light mode to dark mode, the source tree is also changed to dark mode.
Conversely, when macOS changes from dark mode to light mode, the source tree is also changed to light mode.
However, if I shut down the system in dark mode and reboot the system while macOS is in light mode, the source tree is still in dark mode.
Other apps don't work that way. The source tree maintains its final appearance at boot time.