ODT to PDF - anomalies detected between .odt and .docx using .NET

We have a software that uses Aspose.Word and runs on alpine linux containers.
Our customers have always used .docx documents successfully, but now they have started using .odt documents as well and we have noticed some anomalies.

These are the anomalies we found between the source file and the final PDF:

Is there some configuration for .odt that we are ignoring? We searched the documentation but could not find any information.

I attach the source .odt file and the results pdf.
.odt file
output.pdf (213.3 KB)

Thank you very much

@smasini
We have opened the following new ticket(s) in our internal issue tracking system and will deliver their fixes according to the terms mentioned in Free Support Policies.

Issue ID(s): WORDSNET-27553,WORDSNET-27554

You can obtain Paid Support Services if you need support on a priority basis, along with the direct access to our Paid Support management team.

Additional information:
In the Compliance field of the PdfSaveOptions options we use the PDF/A-1b format.
However, we have noticed that if you use the PDF/A-1a format the PDF output is correct.

@smasini Thank you for additional information.