The latest Dexed VST3i (version 0.9.6) binary works fine here on Ubuntu 20.04. Just dragged and dropped into ~/.vst3 folder. Downloaded from here:
https://github.com/asb2m10/dexed/releases
(N.B. there are no VST2 or LV2 versions included with this release).
Distrho are still distributing the older 0.9.4 binaries for VST2 and LV2, which are downloadable from here:
https://distrho.sourceforge.io/ports.php
They also work fine here.