The 21-year-old left-back remained at Club Brugge despite United exploring options in the position during the previous transfer window.
According to Belgian sources, Seys featured prominently on United’s shortlist as the club considered competition and cover for Luke Shaw.
Manchester United ultimately pursued other targets, but their interest in Seys has not disappeared.
Recent reports claim the Premier League club are still monitoring the defender, with scouts continuing to follow his performances for Club Brugge.
Seys has established himself at the Belgian club since making his breakthrough and has also earned international recognition with Belgium.
He was particularly productive during the 2024/25 season, recording five goals and eight assists across 55 competitive appearances.
The defender has continued to contribute this season, providing three assists in his first seven Belgian top-flight appearances.
Seys is under contract with Club Brugge until the summer of 2029, giving the Belgian side a strong negotiating position should United make a formal approach.
The reports suggest United are keeping their options open at left-back after moves for other targets failed to materialise.
Seys therefore remains one of the players being monitored as United consider their longer-term options in the position.
No formal offer has been made for the defender at this stage.