It evidently isn’t reliable and has never provided reliable coverage of the K League.
The most reliable sources are Lingard and FC Seoul. Neither of which said anything about terminating his contract. Because they didn’t, it expired at the end of the season just like Casemiro’s is expiring this summer.
https://m.fcseoul.com/fcapp/newsDetail?SEQ=4168&TYPE=N&START_NUM=6
It was 2 years. Casemiro joined in August 2022 on a 4 year contract. You’ll be surprised to know that it expires at the end of the season, not August 2026.