For the Ukrainian side, prior to May 2024, released POWs were entitled to 90 days of paid leave, and then had to return to duty (if their physical condition allowed that).

With the approval of the new mobilization law, freed POWs have the option of being discharged from service. That’s retroactive and also applies to those who were exchanged before the new law came into effect.

Consequently, they can remain part of the UAF only on a voluntary basis. There is always the 90-day leave for those who choose to stay.

Likely, there is now an emphasis on the individual sense of duty (returning with former comrades-in-arms, etc); providing, to those who do not feel up to it, the chance to return home. Ukrainian lawmakers preferred to focus on the ostracization, on the part of the servicemen, of the idea of imprisonment (torture, deprivation, etc.), rather than on the dishonor historically attached to it, which would require freed POWs to return to active duty to redeem the “shame”. This reflects the sentiment of Ukrainian society, which views their POWs with a great deal of empathy, compassion and solidarity towards their plight.

As for the Russian side, to my knowledge, the exchanged POW is considered a normal servicemen (i.e. either a contract soldier or a mobilized one, either way serving until the end of the “SMO”). Let’s say like a wounded one, to make a comparison. There is a period of rehabilitation, after which either the medical commission decrees that the soldier is unfit for service or, usually, he goes back to the front.