When I select some text to apply a style, it applies to the whole text, not just the text selection. This is happening since the last update to 2.9.24 on Joomla 3.10.9 and I was able to reproduce on multiple sites.
I think I found what might be causing this. All the sites I was able to reproduce the problem on, in the Global Settings, Container Element & Enter Key was set to None : Linebreak. When I switch to Paragraph : Paragraph, it's OK. Can this be fixed?