As I wrote my results with Rustoleum clear "enamel" over several types of cured paint and over vinyl stickers was uneventful: no lifting or wrinkling.
I don't use Krylon (except HAVE used Krystal Kleer acrylic sprays from Krylon and don't think the finish is either durable or smooth).
WHEN IN DOUBT always test first, IF YOU CAN'T TEST you can sometimes get an otherwise bad formula to "play nice" with your delicate paint/decals by giving the surface a VERY LIGHT "dusting/misting coat" first and allow that to fully dry (harden) before GRADUALLY adding some more LIGHT coats and allow generous dry time between each. If you go slow and with luck you build enough protection layers that subsequent heavy coats won't penetrate and soften the goods. YRMV and practice pays dividends.