Mine is long gone. You need to scrub that strip with a brush. I use a toothbrush, you have gunk in there. I would rub a white rag over it first and make sure it is not algae. Every time I get an algae outbreak it starts there.
Mine was like yours and I pulled it off. You could cut it loose where it has already started coming loose.
Keep an eye on it and brush the whole strip and that groove underneath it. I guarantee you will get algae if not cleaned on a regular basis. Try to separate the flap and get in there as well. We don’t use the toothbrushes we get from the dentist so I use those. Check around your skimmer as well. You might have a flap between the faceplate and liner. Another popular spot for algae, the toothbrush works well there as well.