I'm guessing it was someone who held the lynx illegally as pets/ part of a private zoo who couldn't or didn't want to care for them anymore. They were released next to a wildlife park which already cares for big cats so it looks like whoever released them wanted them to be found.
I'm wondering who owned them and if they have other exotic animals. They wouldn't be able to get vet care for them since they would be reported for having wild animals.
It's got to be pretty hard to keep 4 lynx hidden, whoever had them obviously has land to keep them on but they must have staff or visitors who could have spotted them.
Maybe the government could have an amnesty for handing over exotic animals held illegally.
I wonder how old the lynx are, have they been bred in this country?