Can not print text with Qt 5.12.0-1 and canon lbp capt driver

Hello,

I use archlinux 64 bits, and I have a canon lbp 3000 usb printer,

since a recent upgrade of Qt5 I notice that I can not print text from a Qt5 application (like kate from kde, notepadqq),

every attempt of printing a text trigger an error from cups :

{{[CAPTFILTER] Input File Error
paused - "ccp send_data error, exit"}}

{{}}

 and in the debug log of cups I can read this error message :

"This document does not conform to the Adobe Document Structuring Conventions and may not print correctly."

one exception is that I can print PDF files with Qt5 applications (like okular in kde) without problems,

softwares that use GTK library for printing don't have problems (libreoffice, gimp, leafpad),

You can find here detailled debug log from cups :

1) when using Qt5 library the printing fails :
https://pastebin.com/QnfE0UP0

2) when using GTK library there is no problems :
https://pastebin.com/t7

the driver I use for my canon LBP 3000 :
https://aur.archlinux.org/packages/capt-src/

detailed thread in archlinux forum about this problem :
https://bbs.archlinux.org/viewtopic.php?id=243127

at first I thought it was a kde problem, but it seems Qt5.12.0 may be the problem, older versions worked fine (I remember that I could print text without problems with older versions of Qt5)

thanks