For more than a year-and-a-half, Covid and civil unrest generally have combined to create a tremendous demand for firearms. Small, defensive-oriented pistols have especially been coveted. This has resulted in shortages, though the supply side has improved the last three or four months.
In addition, most gun manufacturers (and other manufacturers) will run a line for a specific period of time and then switch to another product. That often leads to periods where a particular model may be in short supply for a time, even in normal times.
My best advice is be patient and keep looking.