With the release of SketchUp Pro 2017 and above  , Trimble introduced a Signed, Invalid and Unsigned "rule" that is displayed under the author in the Extension Manager. This is an arbitrary rule that has nothing to do with how SU Podium, Podium Browser or PodiumxRT or any other Cadalog, Inc. extension functions in SketchUp. Further, Cadalog, Inc. extensions and plug-ins have been in use since SketchUp 7 and have absolutely no security risks.

Extensions manager signed/ unsigned/ Invalid Signature have no effect on the features and functions of SU Podium or PodiumxRT. But there are times when Trimble's own Extensions Signing portal is broken and sometimes the Signed Extension can not be obtained.

Rest assured that being unsigned or invalid has nothing do with how SU Podium is integrated with SketchUp. Being unsigned will not create bug splats or be the cause of any SU Podium bugs.