Go to piefed.ca/admin/site and save the form. Sounds weird but it might help.
Voyager is doing an API call whenever the inbox is loaded and that API call includes some data from that form and the underlying structure of it all got changed a few weeks ago. Saving the form will flush out the gremlins. If your sidebar text vanishes after saving the form, here it is so you can paste it back in and save a second time:
** A Canadian-run community, geared towards Canadians, but all are welcome! **
That was my only guess. The Voyager dev would be better placed to answer this.