Quoted from RandyW:
I sanded, filled, sanded, filled and sanded and filled until it was good enough for me. Don’t like it, don’t worry. It won’t be in your house.
The bubble you highlighted was from the wet application method. It is since fixed. One spot is a run in the corner that wasn’t visible until the vinyl touched it. The rest, aren’t even visible in person.
Best reply ever!