Cant find how to "toPEM" after upgrade

[citkane]

I have been successfully using jose [1.26.1] to generate .pem file as described in this previous dicussion.

After upgrading to [4.8.1], I can't find a way to reproduce this functionality.
I replace:
const privateKey = jose.JWK.generateSync('RSA', 2048);
with:
const { publicKey, privateKey }= await generateKeyPair('RSA-OAEP', 2048);
in order to get a keypair,
but then:
privateKey.toPEM(true)
yields the error:
TypeError: privateKey.toPEM is not a function

Has toPem been deprecated?
Maybe I am missing something obvious, but I can't find how to do this in the documentation.

Help appreciated please.

[panva]

There are individual key export functions.