There’s no problem with the delivery of ads, TWiT is amongst the best, if not the best, in the business at delivering ads. The problem is that advertisers are cutting their ad spending because they don’t know how much income they’re going to have in the coming weeks and months. Share prices are down too, which means that the usual sources of investment for those advertisers are drying up - borrowing is difficult if your stock price is tanking.
What makes it worse is that the number of listeners for each podcast has fallen, most likely because of the loss of captive commute time that many people filled with podcasts. This probably makes getting advertisers in harder work for TWiT if the audience appears to be in decline, even though it’s a one-time consequence of the “shelter in place” situation.
It’s a tough time for TWiT, and podcasts that are failing to generate ad income are going to be at risk, no matter how good the content. All we can do is be as understanding as possible of the pressures Leo & Lisa are under, and tell as many people as possible how good the shows are. Leaving reviews for shows on iTunes and other places will help keep them visible to new audiences too.