This is an auto-filed bug because app-backup/spideroak-bin installs files with unresolved SONAME dependencies.
The issue was originally discovered on amd64, but it may be reproducible on other arches as well.
If you think that a different summary clarifies the issue better, feel free to change it.
Attached build log and emerge --info.
Created attachment 642806 [details]
build log and emerge --info