Currency
If you are updating, the biggest thing for you is the new currency settings. The config has added 2 new options for a currency prefix and suffix to avoid having to change every message in the language.yml.
Updating won't add anything to the prefix or suffix in the config

MySQL
There is now support for MySQL. You can find the options in the config. If the plugin doesn't connect to an SQL server, then it will default to local storage. Similarly, if migrate-local-data is enabled in the config, all of the locally stored bounties will be moved into the database.

Another bonus option in the config is auto-connect. With this enabled, NotBounties will try to connect to a database every 30 seconds if one isn't already connected.

Bounty Leaderboards
There are new commands that will show your own bounty stats as well as top bounty stats.

/bounty top (all/kills/claimed/deaths/set/immunity) - Lists the top 10 players with the respective stats.
/bounty stat (all/kills/claimed/deaths/set/immunity) - View your bounty stats.

Most of these were already recorded with placeholders, but now, you can see them without any external plugins. The players just need the notbounties.view permission. There was one placeholder that was added that is "claimed" in the command and "%notbounties_currency_gained%" for the placeholder.

With these new commands, there are new options in the language.yml.

In the future, I plan on adding an area in the GUI to view bounty stats. Overall, this has been a decently large update, especially with MySQL. Although I do test my plugins before updates, it is getting harder and harder the more features I add. That being said, if you do see any bugs at all, send me a message either here or on discord.