The bootstrap version is what first starts up the agent which can then be updated after it connects to the server (hence why it is lower than the agent version in your screenshot). This is how the automatic updates work.
You rarely need to update the bootstrap version which is essentially done by reinstalling the agent. Only when it is very very old do you need to reinstall it. Right now anything newer than bootstrap 6.0 is supported (i.e. tested). If you ever do need to update it there are directions here: