Thanks ajlittoz, sorry for not providing details in my original message. Unfortunately I cannot already edit it since I’ve lost much time trying to investigate the situation further with different LO versions.
Let me share the detailed info.
XForms documents and web apps (client/server pairs)
I have my own Web application deployed under WildFly 23 and my own XForms document.
I also have the well-known J. David Eisenberg’s example with the CGI script deployed under Apache 2.4 (Debian 10)
I tested several versions of LO under windows 7 (32 bit). Java version 1.8.0_321.
I uninstalled existing version before installing the other.
Each version was installed with default options.
The following results were the same for both client/server pairs.
versions 18.104.22.168 and 22.214.171.124 work as expected.
version 126.96.36.199 has a probable bug: seems like it sends an empty document.
version 188.8.131.52 sends XML as expected but does not handle the response properly: the instance data remains unchanged. This is also true for x86-64 version under Debian 10, OpenJDK 11.
version 184.108.40.206 (the latest for now): after opening the document all controls are marked red as if the bindings were wrong. While submitting I get a message box about wrong data and then the server error. No data is being sent.
Hope my info will be useful.