# Why exported text ends with a highlighted percent symbol?

I have recently updated Mathematica to 12.1. Whenever I export strings as text now, as in the following MWE:

    Export["test.txt", "a", "Text"]


a highlighted question mark appears at the very end of the underlying txt file:

Then I need to put extra effort to remove. How I can avoid this problem?

• I suspect that you are opening in an editor that uses this convention to warn you of a missing eol. – Alan Oct 5 '20 at 18:01
• Look at test.txt in a hex editor and it should only contain a single byte 0x61. – flinty Oct 5 '20 at 18:02

Export["test.txt", "a\n", "Text"]