election.ansidev.xyz is configured as CNAME for election.safestudio.tech? I wouldnt have expected that work in the first place, however assuming both domains belong to the same Cloudflare account it might the exception for such a cross-domain reference.
The thanhnienthuduc CNAME however cant work as Cloudflare does not know about that domain. You’d need to add it first to the same account, after which a configured CNAME would likely work just as in the case of the first two domains.