Brunner, 20, has been enjoying a productive spell with Monaco, but according to Sky, the forward is not expected to be included in Klopp's selection for the November fixtures.
The former Borussia Dortmund youngster has reportedly scored eight goals in 11 appearances this season, putting himself in contention for a senior international opportunity.
However, Klopp has opted to bring back Füllkrug, who has been in outstanding form since returning to Werder Bremen on loan from West Ham United.
The 33-year-old has scored nine Bundesliga goals and currently leads the division's scoring charts, making a strong case for a return to the national team.
Füllkrug has not represented Germany since June 2025, but his performances in Bremen have made him difficult to overlook. He has scored 14 goals in 24 previous appearances for his country.
The striker's recall has now been confirmed as part of Klopp's 24-man squad, while Brunner will have to wait for another opportunity.
Germany face Serbia in Belgrade on November 13 before hosting the Netherlands in Berlin three days later. The matches are the final two fixtures of the Nations League group stage, with Klopp looking to strengthen his team's position ahead of the knockout rounds.
Brunner's omission is a setback, particularly given his recent scoring record, but his form at Monaco should keep him in the conversation for future selections.
For Füllkrug, meanwhile, the return represents a reward for his immediate impact back in the Bundesliga and an opportunity to re-establish himself in the Germany attack.