Have just upgraded to macOS Big Sur and now see the message ‘Indexing failed for (my) iMac’. I remember having to make some change many months ago for a similar issue, but don’t remember what I did exactly, something with SMB sharing. Has worked perfectly since then.
macOS Big Sur 11.0.1
Apple TV tvOS 14.2
Infuse Pro 6.5.4 (3348)
I see the same issue on iPhone and iPad apps, both 14.2.