I couldn’t find any info on a shortage or anything but it’s been out of stock at every local store I’ve been to for the past month at least. I finally found some a few days ago at Costco (who were out last time I went) so hopefully the availability is getting better
This is how the humidifier I used in the 90s worked. Tub with water, vertical sponge and a fan blowing over the sponge. I’m sure these are still out there but the little misters they call humidifiers now don’t work well.