Investors often talk about the opportunity that comes with a recession. The trick is having the resources in place to capitalize on those opportunities. The same is true for philanthropic investment. When the economy is booming like it is now, costs generally increase and overall suffering, at least financial suffering, generally decreases. The construction industry provides a salient example. Construction is often the hardest and fastest hit of any recession. Right now, many construction companies are working at capacity and prices (along with profits, employment, worker incomes) have been steadily increasing for ten straight years. After the last recession construction prices plummeted as contractors were desperate for work. And at the same time, charitable giving, along with consumer spending, cratered. When the next recession comes, most charities will be in the same position they were in 2008-2009: running out of money and having to retract services.
There was a post few months ago pointing out that charities aren't doing enough to prepare for recession. This means that charities are squandering their donations by spending them as fast as they get them. When the next recession comes, they'll be unable to alleviate the added suffering and may be forced to retract services when people need them most and when those services are likely getting more affordable.
I suspect much of the trouble is the same as the trouble investors have trying to take advantage of this strategy: it requires marking a better prediction than the prediction the market is implicitly making with its current prices. Although it seems reasonable to predict that a recession will come "soon" since it's been unusually long since the last one and they appear cyclically (approximately coordinated with the approximately 5-year business cycle?), making that prediction too soon and switching to hoarding assets in anticipation of a drop so you can re-buy assets when they are at the bottom to maximize gains on the way back up will result in unnecessarily giving up potential gains. You might make a lucky guess once, but in the long run you'd need some reason to believe you can predict recessions or else you will perform worse than the market, not better.
So this seems probably only relevant if you are so good at predicting recessions so you can use that to make money and then donate that money, and will probably also require keeping quiet about your prediction and your evidence such that you can maximize the amount of advantage you can take (up to the limit of your funds, including the use of leverage, which might cause you to carefully share your knowledge in an attempt to fill gaps in opportunity you wouldn't be able to take advantage of yourself). If you're a non-profit, regular donor, or anyone else, you're probably best off not trying to beat the market, and only accounting for this in the normal way of holding funds in reserve so you can weather temporarily shocks to the market, i.e. have enough operating capital that you won't have to draw down on your investments before they recover.