Both my desktop and laptop, Ubuntu 20.04, just updated the nextcloud client. Neither machine now displays the nextcloud icon? Nextcloud appears to be running in the background.
Not sure but I have this issue with KDE Plasma: 5.18.8 on Ubuntu 20.04 LTS where Qt version is 5.12.8 I tried with the nextcloud-desktop version 2.6.2-1 and 3.4.4-20220318 from the PPA without a better result