Not making an accusation, but it reminds me of a chat transcript oddity I saw while using opencode back in August. It replace a syllable of a word with a punctuation mark that has the same pronunciation or HTML entity. It was something like "...the &litude of that waveform..." but I can't remember exactly, nor which model I was using. I just noticed it and thought, that's weird. A few days later I read about text watermarking and figured it may be that.

ChatGPT sometimes spit out some characters from very foreign character sets. Maybe only an issue on the free side?