Some people are reading into him being "released". The reality in Scandinavian football is that most players are on short contracts (barring a small core) - especially a club like Sarpsborg which was in danger of relegation. He only signed for them in September - presumably to get at least some football before the Scandinavian seasons shut down over winter either with a view to getting a new club over the winter or to win a move back into central Europe.
The financial realities of playing in the top league in Norway and the second tier are stark so teams at the lower end of the league typically offer short contracts - especially during the season. There is little to nothing to be read into this in terms of his quality.