What knock-on effects would happen if Medical Education were free?

I try to be mindful of my political opinions, and I've been trying to come up with a downside to this policy – but I'm certain there are some. Even pop-economists like Tim Harford are able to come up with unintended consequences. My question:

In countries with single-payer or government-managed healthcare, what negative impacts would the following have:

• The government/national healthcare provider assumes the cost of debt for training Doctors, Nurses and Dentists.
• There is no loan repayment from these people until they have either served (for example) 15 years with that institution – at which point the loan is written off.
• If they quit to either move into private healthcare or leave the field, they assume the balance of their debt at the time of their departure.
• The debts would be structured so that leaving the country is not a way to avoid the debts (to my knowledge, there are mostly reciprocity agreements between governments that allow the pursuit of certain debts or crimes, which would have to be expanded).

In the UK we had 23,838 doctors graduate in 2022, with the cost of their training (to them) being about £55,000. It seems that with an NHS budget of £188 Billion, and additional £1.31b to secure the supply chain would be a good investment.

Are there any consequences to this plan that I'm not seeing?

Apologies if this breaks the rules, I am just hoping for some educated, grounded opinions rather than the gut-feel, politically motivated mud-slinging that most subs devolve into.