A few weeks back I have aquired a domain name on Google DNS and i would like to change nameservers to cloudflare. Following Cloudflares Documentation https://support.cloudflare.com/hc/en-us/articles/205195708
I have disabled DNSSEC and changed Nameserver accordingly:
My Cloudflare Dashboard shows following Nameserves

Google DNS Nameserver Settings
I changed it last friday and its still not completely propagated. ICANN lookup still show Gcloud Nameservers https://lookup.icann.org/lookup
DNS Lookup shows a mix of old and new config. https://www.whatsmydns.net/#NS/luctrate.com
Google api still shows old nameserver. https://domainsrdap.googleapis.com/v1/domain/LUCTRATE.COM
Do you have any clues of whats going on here?

I can see that the record have been propagate correctly.
So to recap my comment for better visibility:
If you want to manage domains purchased from google on another website (e.g. OVH, GoDaddy, Cloudlare, etc.) you must change name servers on domains.google as described here.
This change may take up to 72 hours, although is usually faster.
You can check current state of NS records with sites like whatsmyDNS or by commands: