The versions-maven-plugin, by default, does not ignore versions ending with qualifier strings when searching for the latest version of an artifact.
For example, versions ending with -alpha.14, -beta3, -M-2, and -RC1 will be considered as valid upgrade candidates.
Suppose your project depends on version 3.2.1 of a certain artifact and then 3.3.0-beta is released.
The versions-maven-plugin will, by default, consider that to be a valid upgrade.