Pasting into Pages no longer keeps original mixed formatting

In Pages (and other macOS apps), under the Edit menu, there's the option to Paste and Match Style and Paste and Retain Style. Have you tried the Retain Style pasting option? That could be your solution.

Being that I don't know the exact formatted text you're trying to paste from LO to Pages, I opened LO and experimented on my own.

I copied some formatted text that included, headings, different fonts, and subscript/superscript text, and found that my copied text transferred into my text box, fully formatted. I did notice that the size of the text box I created in my Pages document, affected the display of the information copied into the text box. Once I fiddled with the size of the text box, my formatted text started to look the way it did in the LO document.

Is it possible that the size of your text box could be the culprit of your text not being displayed as you want?

You have to take into consideration that formatting codes between Pages and LO are very different and you also have to take into account the difference in fonts, font sizes, and styles. Complex formatting features, such as tables, graphics, or specific styles, may not be fully supported or may be interpreted differently between Pages and LO and that could be the issue.

You may have to save your information in LO to a Word .docx file and then import it into Pages to possibly get the desired display/layout that you want.

Applications are designed to copy and accept specific pre-programmed application data sources to and from the clipboard. The LibreOffice Writer 7.6.4 content that was copied to the clipboard, regardless of the type of paste selected in Pages, arrived in Text box, or body text as just plain text.

The text that I copied from LibreOffice Writer to the clipboard was a 2 sentence paragraph with non-contiguous highlighted text and another segment of that text that was both highlighted and underlined.

The same LibreOffice Writer clipboard content pasted into a Rich Text configured TextEdit document as plain text too. Regardless of type of paste.

Just a simple paste into MS Word 16.80 produced the expected attributed text that matches what was copied from LIbreOffice Writer to the clipboard. The receiving application makes a difference.

Tested: macOS 14.2.1, LibreOffice 7.6.4, Pages v13.2, TextEdit, Word 16.80

The hosting software booted me before I could finish the above content. It should read:

Applications are designed to copy and accept specific pre-programmed application data sources to and from the clipboard. The LibreOffice Writer 7.6.4 content that was copied to the clipboard arrived in the body text, or Text box of Pages with only the underline surviving. A Paste and match style eliminated even the underline.

In TextEdit configured as a Rich Text format document behaved in the same manner as Pages above (without Text box capability).

Everything else remains as written previously.

After shutting down the M2 Mini Pro (Sonoma 14.2.1) overnight, I find that selected Rich Text content in an open LibreOffice Writer (7.6.4) document, when copied and then using only a simple paste in Pages deposits in identical appearance to the LO content with the exception of the original yellow highlighted text.

LibreOffice Writer 7.6.4:

Pages v13.2:

So neither option you have available pastes the copied information the way you want it to? In LibreOffice, do you have the compatibility settings in the LIbreOffice/Writer, Advanced, and Accessibility options set properly?