Most film is put on the inside. If you're putting this on the outside of the slider (correctly) the mirror will be facing in. Can you install it *backwards* mirror out to hide the flaw?
I recently installed a mirror film from Home Depot that's called a titanium finish and notice that under certain light conditions you can't tell it's mirrored. For sure when it's lighter in the room than outside the mirror effect is invisible.
14 RAV4 2.5 5W-20 PP
18 Nissan Titan 5.6 DI, 0W-20 QSUD
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