Does Chess.com's computer have less good days?

I'm puzzled by the disparity of my results when playing against the 'play computer' function. I'm often outclased in game after game on level 7. Yet, I have drawn and won on level 9.

Certainly, I'm uneven - but am I that uneven? While I would like to believe that I occasionally perform far above my usual intermediary level: when I checked one of the won games on level 9, my impression was that the computer rather did not play as well as I would expect on that level (for instance, it lost a piece in the middle game despite not being forced and without gaining any obvious advantage).

So, am I imagining a sometimes shifting quality in the 'play computer' function? Has anyone else noticed this? If so, could it be high traffic and strained memory capacity playing tricks?

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