The Dictionary App Builder program is calling Gradle to do some of the work of building the app.
I think the --warning-mode=none is an option on the Gradle call telling Gradle to suppress all warning messages. So, it would seem this is not a warning being displayed, but rather a command to Gradle not to display any warnings.
I agree with @drowe it is just a parameter that is being passed to gradle to tell it to not show so much feedback.
If you install Gradle separately to the DAB installed Gradle, then in the past that has caused some build issues. DAB is for non programmers so the assumption is that you don’t have a separate Gradle installation.
In most programming a warning is not a an error. An error stops a build process. A warning does not stop the build process.
Directory of C:\Users\Kells\AppData\Local\Temp\App Builder\build\DAB.003\a\build\outputs\apk\release
07/14/2023 01:19 AM <DIR> .
07/14/2023 01:19 AM <DIR> ..
07/14/2023 01:19 AM 9,085,599 a-release.apk
07/14/2023 01:19 AM 375 output-metadata.json
2 File(s) 9,085,974 bytes
2 Dir(s) 73,647,656,960 bytes free
Copying APK to output folder
The filename, directory name, or volume label syntax is incorrect.
0 file(s) copied.
1 file(s) copied.
Android APK built successfully.
The filename, directory name, or volume label syntax is incorrect.
The system cannot find the path specified.