In https://github.com/elastic/elasticsearch/pull/88639 we introduced a new setting that allows configuring a maximum headroom in disk watermarks that helps reducing the waste of disk space in large disks. The disk health indicator should take that new setting into account to avoid reporting issues when there's still room for new data in the cluster. 

https://github.com/elastic/elasticsearch/blob/6ec31ed1533e6aaf8fc6dabda5e419f5dce984fa/server/src/main/java/org/elasticsearch/health/metadata/HealthMetadata.java#L193-L199

Those calls should take into account the available max headroom.
server/src/main/java/org/elasticsearch/health/metadata/HealthMetadata.java
return floodStageMaxHeadroom(ByteSizeValue.parseBytesSizeValue(floodStageMaxHeadroom, setting));
            }
            public Disk.Builder frozenFloodStageWatermark(RelativeByteSizeValue frozenFloodStageWatermark) {
                this.frozenFloodStageWatermark = frozenFloodStageWatermark;
                return this;
            }
            public Disk.Builder frozenFloodStageWatermark(String frozenFloodStageWatermark, String setting) {
                return frozenFloodStageWatermark(RelativeByteSizeValue.parseRelativeByteSizeValue(frozenFloodStageWatermark, setting));
            }
            public Disk.Builder frozenFloodStageMaxHeadroom(ByteSizeValue frozenFloodStageMaxHeadroom) {
                this.frozenFloodStageMaxHeadroom = frozenFloodStageMaxHeadroom;
                return this;
            }
            public Disk.Builder frozenFloodStageMaxHeadroom(String frozenFloodStageMaxHeadroom, String setting) {
                return frozenFloodStageMaxHeadroom(ByteSizeValue.parseBytesSizeValue(frozenFloodStageMaxHeadroom, setting));
            }
            public Disk build() {
                return new Disk(
                    highWatermark,
                    highMaxHeadroom,
                    floodStageWatermark,
                    floodStageMaxHeadroom,
                    frozenFloodStageWatermark,
                    frozenFloodStageMaxHeadroom
                );
            }
        }
    }
}