Having had a look today at mine (cos I've got to fill in some veeeery boring forms), I've noticed a number of requests for "Identity Verification" and "Identity Check to comply with Anti Money Laundering Regulations" made to the credit reference agency (CRA) made by companies I've used for Crypto purchasing and similar to those mentioned on this forum in the past such as Revolut and betting companies.
Now, I don't know what information is being exchanged at the back end, as that depends on the agreement held between the company and the CRA. I suspect it's just taking the details I provide such as my name, address, DOB etc. then passing that over to the credit agency who respond "yay", "nay" or "no information held". However, the company can also request more information such as what the credit agency has your DOB written down as (more applicable if you use a real information with a modified DOB). Do this repeatedly and the CRA (who you've never directly interacted with) may end up noting you down as a potentially fraudulent person and informing authorities, as that's their purpose in life and that's how they make their profits.
Just because you're under 18, it doesn't mean you have no credit record (which is a hugely important document that holds mounds of information about you) - it just means you can't see that record, and no company can offer you a loan or credit. Things get 1000 times more serious as soon as you use a fake for fraud, the usual rules of "the police will just give you a warning at most then fuck off" do not necessarily apply - so do be careful.