Ronaldo joined Al-Nassr after leaving Manchester United in December 2022, becoming the best-paid player in football history with an annual salary of £177m.
The club, who have won 10 Saudi Pro League titles, called the signing “history in the making” but Ronaldo has only won the Arab Club Champions Cup in 2023 since the move.
The five-time Ballon d’Or winner signed a new two-year contract in June 2025.
Both Al-Nassr and Al-Hilal – the country’s most successful club with 19 league titles – are among the teams controlled by the PIF, which also backs Newcastle United.
BBC Sport has been told former Real Madrid team-mate Karim Benzema’s move to league leaders Al-Hilal from Al‑Ittihad earlier this week was the principle reason for Ronaldo’s frustration at Al-Nassr.
French striker Benzema, 38, scored a hat-trick on his debut for Al-Hilal in a 6-0 win over Al-Okhdood on Thursday.
Al-Nassr are second in the league, one point behind leaders Al-Hilal, with both having played 20 matches so far this season.