Comment by ofrzeta

I kind of tried to replicate your experiment (in German where "Erdbeere" has 4 E) that went the same way. The interesting thing was that after I pointed out the error I couldn't get it to doubt the result again. It stuck to the correct answer that seemed kind of "reinforced".

It was also interesting to observe how GPT (4o) even tried to prove/illustrate the result typographically by placing the same word four times and putting the respective letter in bold font (without being prompted to do that).