OctoPrint's bundled FirmwareCheck plugin has been updated to also give you a short heads-up if you are running a development build of your firmware.
This is nothing to be alarmed about, but you should at least be aware that you are not running a final release version, and from our experience on OctoPrint's support channels we had to find that a lot of people aren't, hence the introduction of this short info. Running a development build means that more bugs might arise that also negatively influence the communication with OctoPrint and that you should be on the lookout for any kind of announcements or warnings both on OctoPrint's side and the firmware's side regarding current problems with the development versions.
If you are a more advanced user who regularly builds and flashes their own firmware or maybe even participates in ongoing development, first of all, good on you 
, and second of all, you can safely get rid of this info once and for all by clicking the conveniently provided link that says Disable firmware checks of severity "info" right below it.
If you are a new user, have no idea what all this means and were directed to flash this firmware by a third party, please be advised that you are running a version that is still being in active development, might be more or less stable depending on what specific build you flashed. If you do not plan or are not able to flash a stable build, you should at least make sure to update your firmware to the latest development builds regularly so that you get bug fixes.
Currently the plugin will detect the current development builds:
- Marlin
bugfix-builds, regardless of version, identified throughMarlin bugfix-in the firmware name
"This is a stupid feature, I regularly test out fresh builds on my printer and now I have this stupid message about it!"
As mentioned above, just click the link conveniently located right underneath the info that says Disable firmware checks of severity "info" to get rid of it once and for all.
It is great that you are aware of running a development build and know that issues might arise and also how to solve them. Not everyone in the 3d printing community or using OctoPrint is and does, so show some sympathy please, we all were newbies once and needed some direction.