Using the Mobile app on Droid V10.0.1150 in the default “Light theme”, when you have Conversatiions enabled, the background “behind the number” at the far right of the subject is too light and so its hard to notice / see the number of messages in the conversation at a glance scrolling down the page.
If you change to Dark Theme the conversation number is really easy to see the number of messages as is white on a Dark background.
But in the default Light theme, the number appears to be a light grey on a lighter grey background so its way harder to see. If the number is already black, then it needs to be a eg: bold black font.
So suggest to make the conversation number black or darker black. Also maybe put an eg: thin black outline around the light background colour edge, and maybe too a slightly darker background colour.
Just so the message number stands out more in the default light theme when you sre scrolling down.