Where are all thejuniors/graduates?

Hello everyone!

I've been hiring developers over the years and one thing that seems to strike me every time is

If I list the job on Indeed probably 99% of applicants are non British recently immigrated etc.

I have no issue with this, but where are the UK university graduates going?

Is it just the UK outputs mainly python Devs? Is everyone just going overseas?

Based in Kent we hire juniors on 34k~ so above typical salaries for the area I believe, I'm just a bit confused.

Do unis just strictly recommend recruitment agencies only? Am I firing into an empty pond with Indeed?