It means that seeed studio has abandoned the reSpeaker products, but keep making them because there are some companies that have integrated them into products, so seeed is still manufacturing the hardware, even though they’ve abandoned the software.
Although it appears that someone very helpfully via https://github.com/HinTak/seeed-voicecard repository is maintaining, at least a little bit, the installation source code for newer Raspbian versions.
However seeed apparently can’t be bothered to tell people this on the store page or their wiki docs.