What are the brown marks on these leaves?

I’ve been away for a few days, left her in a bright indirect location (to my best judgement). I came back and found these odd markings. Note, it isn’t on all of the leaves. Only some of them. They day I got it, I let it sit on my sheltered porch in the afternoon sun for a hour or two. I didn’t think it was too harsh, Could I have been wrong?