Hi Apollon, Thank you for the diagnostic and the reassignment.
> This is most likely GHC bug #15260[1], which has been fixed in GHC > 8.4.4. Hopefully, the next upload of xmobar will behave correctly. Maybe it would make sense to request a rebuild of xmobar now that ghc 8.4.4 is in testing? Or is there a new version of the xmobar package coming soon? Best regards, Samuel