Hi @Matteo,
I understand you turn a stringified decimal right back to decimal because of a bug (or a lack) in sequelize, using a sequelize getter.
The following is working on my side:
// Using:
const value = this.dataValues['providerCommissionsPercentage'];
// instead of:
const value = this.getDataValue('providerCommissionsPercentage')
Let say if it helps.
If not, please let me know if the field is working (as a string) without de getter.