It's a simple characterset collision; basically we USED to store our default characterset as:
And now store the default as:
This is for standards compliance, we follow current web standards and they have moved away from the old "Latin alphabet no. 1" in favor of the newer Unicode Standard
(its how we can insert emoticons and non-latin characters 👍).
To "fix" it you just change the "CHARSET" value in the /languages/english/generic.php file, or you can "convert" to the newer characterset by following the steps of the conversion tool in the Control Panel (CP -> Tools & Information -> Content Rebuilder -> Transision Actions -> "Update All Tables to UTF8mb4"). If you choose to convert please ensure you have a backup.
Either way, there is tons of reading on this topic here if you use the search, "diamonds", "utf", or "UTF8mb4" are some keywords for starters.