Start a new presentation document. Set layout to "Blank Slide". Open the styles section of the sidebar and set "Drawing Styles" to show mode "All styles". Open the file https://docs.oasis-open.org/office/OpenDocument/v1.3/os/part3-schema/OpenDocument-v1.3-os-part3-schema.odt in Writer. I have chosen this file, because I know it has a lot of paragraph styles. Go to section 2.2.6 in this document in Writer and copy the content of the section to clipboard. Go to the presentation document and create a text box by dragging. Insert the clipboard as "Rich text formatting (RTF)" into the text box. Look at the sidebar. You have got tons of useless styles. For each paragraph style in Writer, LibreOffice has generated a "Drawing Object" style.
Reproducible Version: 25.2.0.0.alpha0+ (X86_64) / LibreOffice Community Build ID: dc9486f2443fa52588b625c0a2a288bff56a7a45 CPU threads: 16; OS: Windows 11 X86_64 (10.0 build 22631); UI render: Skia/Raster; VCL: win Locale: es-ES (es_ES); UI: en-US Calc: CL threaded If I am not wrong, it also happens with the normal paste, just after create the text box, click on their text and [Ctrl+V]