After you enter in Safe mode and come back, the theme I had before entering in Safe mode is not coming back. the default one is applied. just put it out there hopping that this faulty behaviour will be fixed.
This is intended behavior since safe mode is usually a feature meant for a small minority of users who are having trouble with their phones. The reasoning behind it is lets say that you installed a rogue theme where the background, all icons, all menus, UI and even the font were changed to pitch black and you think that your phone was bricked. Then you learn of safe mode and suddenly you can use your phone again and see the menus. Now lets say you don't know how to change your theme
If safe mode did not reset your theme upon rebooting out of safe mode, then you would have the same problem prior to you being in safe mode to begin with