Perhaps, when the pandemic hit in Feb/Mar, they had 6+ months of Study articles lined up already and, thinking the pandemic might blow over by the summer, they decided just to go with what they’ve got rather than revise anything.
By the time it got to the Autumn they might have thought, if we start including references to the pandemic in study articles now, then perhaps normality will be returning just as the new articles start rolling out, and we'll look stupid for beginning to cover the pandemic just at the point it’s beginning to get better.,
“In for a penny, in for a pound”, they might just ride out the whole pandemic without ever addressing it at their main study meeting. “Food at the proper time”, indeed.
*Unless I’ve missed references to the pandemic in the Watchtower study articles, I confess I’ve not read them all. It just seems odd.