According to Mouser, Xilinx now quotes 44 to 48 week lead times for their Spartan-6 and Spartan-7 series. There is limited stock for some types (at Xilinx and other distributors), and back-orders with October or November ship dates for others.
Is that Xilinx' normal lead time, or are they experiencing shortages due to Covid-19 or other reasons? Their Spartan-6 web page still claims "12 weeks"... https://www.xilinx.com/products/silicon-devices/fpga/spartan-6.html
My experience is 14 weeks is a typical lead time from the factory. Once lead times stretch out beyond half a year, they are basically saying, we'll let you know when something becomes available. They are going to keep their bigger customers happy as much as possible and will happily ship product planned for you to any larger customer. I've had distributors do this and there was nothing I could do about it, even though they acknowledged my reel came in and they gave it to someone else.
So when lead times stretch out the small guys are always screwed. Get parts when and where you can.