I'm sure this has been mentioned before, but what about article titles which contain parentheses that actually are part of the name of the subject? The page preview seems to work with chemical elements that have parentheses in the title, but looking at the preview for Brandy (You're a Fine Girl) leaves out the remainder of the song title which is in parentheses.
Topic on Talk:Page Previews/Flow
I think this has been discussed previously but I'm not sure what the current thoughts are on it. I've opened a ticket for discussion with the maintainers: T226323.
Currently anything in parentheses is hidden in the preview, but I think anything in bold should be shown.
This could be implemented generally as a LocalSettings variable containing a list of terms, which when found within the text of a page, cause the parenthetical stripping to be disabled. Another solution is to have a LocalSettings variable containing a RegEx for parenthetical text that should be included in Page Preview. ~~~~
Another user case where this is a major problem is with Bios. The subject's DOB and DD are usually within parentheses immediately following their name. e.g., John Doe (26 BCE - January 1, 1955). When I come across an unfamiliar name while reading WP, I almost always need to know the time period when the person lived (and most of time that's all I need to know about them), however, Page Preview doesn't show the dates. Maybe when fixing the other parentheses issues you could fix this too (or make sure the fix addresses this user case. ~~~~