This issue does not affect DTTG 4 alone, it was already present in DTTG 3.
Sometimes, when I write a Markdown or text file and enter a word that has been detected as an auto-Wiki Link, all text that I write afterwards is rendered in black instead of white (when using Dark Mode on the iPhone). I recorded the issue:
[YouTube Link[(https://youtube.com/shorts/aEArhs9vTsw?feature=share)
This only affects the editing mode. In view mode, everything is visible again. However, when entering the edit mode again, the affected text is rendered in black again. But, if I close the note completely and reopen it again, everything is correctly rendered and I can continue writing w/o any issues - unless entering another Wiki Link word.
Strangely, the issue does not occur each and every time. I sometimes can write long texts with man auto-detected Wiki Link and the text keeps rendering correctly white text on black background in Dark Mode. This makes it difficult to reproduce the issue and figure out what it might trigger.