WFS with output format "shp" fail to return a zip 9 times out of 10

[bsoufflet]

On QGIS server 3 with the extension installed.
If I run multiple times the following CURL command :

curl -o myshape.zip http://qgisserver.XYZ.com/?exp_filter=ZZZZ&typeName=YYY&VERSION=1.0.0&SERVICE=WFS&outputFormat=SHP&REQUEST=GetFeature&MAP=/path/to/this.qgs

I will get about 9 times (out of 10) a bad ZIP file which cannot be unzip and which is too large with the following response header :

Content-Type: text/xml; charset=utf-8

And about 1 times (out of 10) a good ZIP file with the following response header :

Content-Type: application/x-zipped-shp

[tethysgeco]

Hello, do you have any news about this problem? Thanks in advance