I am an EU national who took out a student finance loan for my fees over a decade ago, so before Brexit.
While it is true that many EU students used to find ways to cheat the system once they went back after their studies, it is incredibly difficult to do this today - if you want to still keep your right to enter the UK in the future, that is.
After living in the UK for a while, I moved back to the EU and every year without fail, SFE contact me asking for updated contact and employment details. They send letters, emails and call you on the phone. They have even contacted my parents, the one time I genuinely did not receive a letter as I was moving house.
Every year I must send proof of address, proof of employment (or further studies, maternity etc) and they assess it over a couple of months and recalculate my minimum monthly repayments. Since gaining employment in the EU, I have been paying £200-300 a month to SFE, which is a much larger amount than would be retained from my paycheck in the UK, thanks to the way they calculate repayments for overseas workers…
I have always been transparent because 1) I still travel to the UK regularly for adhoc work and 2) still hold status under the settlement scheme. If I weren’t honest and made my repayments on time, those privileges could obviously be revoked.
Last year, the UK brought in the pre-travel electronic authorisation, which is linked to your passport etc, so I assume all those EU students using loopholes and disappearing “off the face of the earth” are happy to never travel to the UK again. They would be flagged at the point of entry or not issued a visa / eta, if they appeared on the system as ignoring their legal repayment obligation which they entered into when signing the loan agreement.