Maybe they only do adaptive cruise models on Wednesday and wood trim on the third week of the month. Now to get both you have to wait a month and because the ship leaves in 2 weeks, now you have to wait for the next one.
Semiconductors are the same. Manufacturer lead times are, even in good times, long for many things because they don't hold stock to cover big orders. If you come along and order a million AD4242WTFBBQ-OMGXXX, one of dozens of variants of a chip, they don't have that boxed and ready. You'll have to wait until the fab is doing that variant again.
The problem now is that all the distributor stock that used to keep everyone going while the big orders were scheduled is gone, and the fabs are so slammed that the time to the next free slot is measured in years, not weeks. And that's if the fab is still making that jellybean part at all and hasn't switched to a higher-margin part.