So this is a strange one. Yes, Libre’s updated fully to the current version (6.1).
When I’m using find/replace, if I format the text as well (say I make it bold, etc), it will automatically also change the font to 0pt. As in, the Find/replace window will state that it will be changed to 0pt font.
HOWEVER, once I accept those changes, it still changes to an unwanted size, but on the document, it’s 2pt font, not 0pt. It’s baffling, I know. It just started recently as well, I’ve been using Libre for quite some time. Have done no shortcut changes or anything else that would clue me in to why it’s doing this now.