For example, copy and paste retains the text color (probably by design). So, sometimes I get black text on a black background, when the app is in dark mode.
The editing process to remove the formatting is pretty annoying.
It takes me time to find the edit button, which is buried in the menu but prominent in the desktop version. Then, I have to toggle the HTML mode and delete the retained tags, which on a phone takes time. The desktop version, instead, has a button to remove all formatting.