Hello, thanks for your respond first of all @harsh_1729 @EmmanuelFlossie @claricelin
I have entered the GTINs for the Sizes i have available, so in my case ,demoted : limited performance" means it just wont show the sold out sizes in Google Ads?
What’s also wondering me, is that for some Products i haven’t entered a GTIN at all but dont get the demoted limited performance error. What could be the reason for that?
Also when i save the GTINs i have ready, and save the changes, it first shows that everything is fine without any errors, but after some time the error showing up again.
When i take a look in the Google Merchant Center, at the top left corner is a red box saying “Resolve all issues regarding guidelines and settings that prevent your products from being showcased on Google.”, but when i click on it, it says ,No problems to be fixed here"
But im not able to close the red box for any reason.
When i click on Products → Tab “examination required” Its showing me all the problems i have on my products though.
But anyways, at the end of the day my products should still be fine even its saying demoted performance … correct?
Sorry for all the questions, just trying to make sure there wont be problems when i start my Google Ad Campagne.
Thanks a lot for your help y’all! 
Have a nice evening and kind regards