Image burning too dark then too light

Curious if anyone has run in with this problem before - laser works pretty great for most every project except when burning in “image” mode. It was working great at this as well but all of a sudden it started burning my photos really dark in the beginning and then gets lighter and lighter until its almost gone. I’ve attached two pictures, one portrait on black cardboard where the image almost disappears completely but I turned to power up really high almost at the end (the top white line) - the second picture is on acrylic - you can hardly make out the feet at first and then it gets lighters (the line in the middle in because I moved the acrylic on accident!) I swear I feel like I have checking everything. I would think it would be a power issue, but the laser runs perfectly well for all of my other projects set to “line” or “fill”. Any help would be greatly appreciated!

You using air assist?
I had this issue at one point, and theorized that my lens was collecting smoke/debris as it burned. Turning on a little air flow prevented it for me.