We are using the PDF - Merge Files conenctor to merge PDF files and set bookmarks automatically. On the surface everything looked fine, i.e. booksmarks were displayed with the correct text when we opened the merged pdf file in a PDF Reader like Acrobat or via SharePoint. However when we opened the file with a PDF web viewer (in our case Edge), the bookmarks were displayed in a cryptic way.
In PDF Reader:

In PDF Web viewer:

I also tried not to set bookmarks directy with PDF - Merge Files but with PDF - Generate Bookmarks but the result remained unchanged. I also tried PDF- Flatten or PDF - Linearize before Generate Bookmarks, but it didnt help as well.