Many thanks to SWLing Post contributor, Grayhat, who writes:
With the sponsorship of UNESCO, two “on air” events will take place February and April, 2022. The events will be the UNESCO World Radio Day and the International Marconi Day 2022
12 to 13 February 2022
from 00:00 UTC of 12 Feb to 23:59 UTC of Feb
23 to 25 April 2022
From 00:00 UTC of 23 Apr to 23:59 UTC of 25 Apr
For further information, click on the event names above.
Thank you for the tip! I do note that UNESCO has yet to post details about WRD this year, but I believe they typically publish information only a couple of weeks before the event.