I just spent many hours trying to determine why a previously good and unaltered document had become horrendously formatted. The preview for the odt was correct in nautilus but when opened it looked dissimilar. I tried previous app images, I tried different computers, I knew it wasn’t something I changed because the pdf version of the same doc looked great and it was created after the odt was last modified. I eventually figured out the issue after about 4 hrs.
The font in my odt file wasn’t installed on the computer that authored it nor my other fedora workstation - either it was lost in one of the libre updates, or fedora updates, either way, it was no longer present on either of my systems.
When you open an odt that contains a font that isn’t present it looks like Writer italicizes the font name in the font menu to indicate that it isn’t installed. That is no where near intuitive enough. I believe there needs to be some popup or something to tell you that you are trying to view a document that contains a font you do not have installed. Something to indicate that you are viewing an approximation of the document.