Adding multiple vector layers into GeoJSON file

Question

I have multiple polygons stored in a list like this :

def drawParcel(self, propriete):
    length = len(propriete.name)
    i = 0
    while i < length:
       layer = QgsVectorLayer('Polygon', propriete.name[i], "memory")
       allLayers.append(layer)

I have tried this code but i only get in the json file the last element of my list :

uri ="C:/Users/ilyasse2.0/Documents/SQRLAND/ils.json"  
context = QgsProject.instance().transformContext()  
options = QgsVectorFileWriter.SaveVectorOptions()  
options.driverName = "GeoJson"  
QgsVectorFileWriter.writeAsVectorFormatV2(allLayers[0],uri,context,options) 

#switch mode to append layer instead of overwriting the file  
options.actionOnExistingFile = QgsVectorFileWriter.CreateOrOverwriteLayer 
for layer in allLayers:
    QgsVectorFileWriter.writeAsVectorFormatV2(layer,uri,context,options)

How can i create a GeoJSON file with the list of layers ?