I noticed that if I load one of the nano-theme themes using load-theme, then subsequently disable all themes and load a different (non-nano) theme, and then execute make-frame, the newly created frame still appears to be affected by the previously loaded nano-theme, even though it is no longer active.

Here is an example: the blue theme (tomorrow-night-deepblue-theme) is the one loaded after disabling the nano-theme. However, when I executed make-frame, the newly created frame inherited some colors from the previously loaded nano-theme, despite it no longer being active:

The same issue occurs with other themes as well. For example, with ef-melissa-light, the new frame inherits colors from the previously loaded theme, even though it is no longer active.