I, too, have a 5ml tube of Schmincke Horadam Yellow Orange that claims on the label to be PY153. (Recently purchased, in Feb 2023.) But I have a suspicion this might simply be a printing error. Yellow Orange was introduced as a new colour in 2017 – i.e. long after PY153 was discontinued – and has always been listed in the Schmincke catalogue as PY110.
I, too, have a 5ml tube of Schmincke Horadam Yellow Orange that claims on the label to be PY153. (Recently purchased, in Feb 2023.) But I have a suspicion this might simply be a printing error. Yellow Orange was introduced as a new colour in 2017 – i.e. long after PY153 was discontinued – and has always been listed in the Schmincke catalogue as PY110.