Remove the fake 3m auto adhesive tape and replace with real 3m auto adhesive tape from amazon. Use 3M adhesive promoter as well. Apply it to the surface the tape will be touching. Clean the surface throughly before applying either the tape or the promoter.
Removing the tape off the spoiler should be fairly easy since it’s new. It’s crappy tape however and no matter how much you prep it’ll most likely start to lift in the corners after a while.