hello in TMP there is a discussion about what is a such Staff officer in green with blue collar and silver/white buttons painted by Albrecht Adam at the battle of Mincio in february 1814, the officers of the Generalquartiermeister had black facings and gold lace, and others Staff officers only red instead of blue as you can see and compare with the Mollo/Mansfield's plates in the link below
https://www.napoleon-series.org/military-info/organization/Austria/UniformPlates/Mollo/c_Mollo.html

The painting was sold in 2022 and gas the following notes: Portrait of an Austrian officer on horseback Signed and inscribed ''am Mincio den 8ten Februar 1814'' lower right. Oil on canvas. 38.5 x 47 cm. Restored. Damaged. Damage to frame (52 x 60.5 cm). Provenance: according to the information given by the consignors, owned by the Princely Family of Schwarzenberg. - Owned by Austrian nobilty. We would like to thank Daniel Hohrath M.A., Museum for the Bavarian Army in Ingolstadt, for the further information on the possible identification of the depicted figure.
Feldkriegskommissär would not have worn a sash. That the sash is worn over the shoulder also indicates that the officer serves as a regimental adjudant or ADC, in this case most likely an ADC.