"Okay, time to post about Cyndane for you Theorylanders. I have been discussing with Maria all day. She and I have different opinions on some things in the notes, but she has convinced me that she is right. I believed that there were some issues with her Power level — the Dark One playing tricks to keep everyone guessing — but Maria convinced me her Power really is what it seems . So you can disregard my comment about her being really, really weak and stick with the word I used earlier— 'weakened'." [emphasis mine]

That her Power really is what it seems, contrary to the DO playing tricks to keep everyone guessing, makes clear that Cyndane truly lost a part of her OP strength.

Besides that, obviously Cyndane doesn't do everything to appear as another person, because she openly shows similar emotions like Lanfear had, e.g. regarding Rand. Doubt that she would voluntarily restrict her own OP strength. Otherwise she certainly would have regretted this in her fight with Alivia. Also her name, "Last chance", is actually quite telling.