Weird error with subdomains

this is so annoying for the past 4 months for me.
randomly when i add some subdomains or change them they dont work anymore.
why is this happening? this is so annoying so before changing to another dns, i want to just know why
is this happening…its like i added a simple A or chame or SRV record and it does not work at all
It said in the cloudflare pannel that its added but its not wth…i cannot understand this

Can you be more specific?

Did you add a corresponding subdomain at a host? If you set that DNS record to :grey:, does it work?