All cable systems in the US are mandated to supply users with those "CableCards" if they request them to decrypt cable tv channels, so you can use your own tuners and not be forced to rent one forever from the cable company. So, it wasn't just Dish. TiVo also uses them. The first one was free and the second one was $1.50/mo. Each could decrypt 4 simultaneous channels. I used them for about 15 years until cancelling cable earlier in the year. $1.50 vs a $30 cable box saved quite a bit over the years.

Here's the page on xfinity for them. They're just PCMCIA cards, which used to be popular. My first laptop had a PCMCIA port which I used for a GPS device in the 90s before they were all-in-one chips. https://www.xfinity.com/support/articles/about-cablecards