Have you done a forum search, magnifying glass icon upper right, to find and read the various threads that discuss each new firmware upgrade? For example the current v4.x firmware discussion thread:
https://community.wd.com/t/firmware-04-04-03-113-discussion/164941
Only YOU can make the determination based on your needs if upgrading to the latest firmware, or a version later than 03.04.01-230 is warranted or needed. In almost every case new firmware versions fix certain issues but almost always introduce other issues. And sometimes, long standing firmware issues are not addressed or fixed at all. One can choose to manually update to any firmware version between 03.04.01-230 and 04-04-03-113 if they so desire. See the following link for an unofficial listing of firmware and links to download them.
https://community.wd.com/t/wd-my-cloud-v4-x-and-v2-x-firmware-versions-download-links/148533
One side note. If one has "unbricked "their My Cloud to a v3.x version firmware, some (including myself) have experienced problems with the Dashboard no longer being accessible when upgrading to a v4.x version firmware (usually jumping from the v3.x firmware direct to the latest v4.x firmware after unbrick). One can read the following thread where I discussed my experience (and solution that worked in my case) with this particular issue.
https://community.wd.com/t/unbrick-then-firmware-upgrade-equals-no-dashboard/136666
