I finally replaced it about a month ago with an onn streaming box from Walmart for about 20 bucks--less than I paid for the original Chromecast a decade ago:
https://www.walmart.com/ip/onn-Google-TV-4K-Streaming-Box-Ne...
Works great, and still has Chromecast support. Most of the stuff I used to cast can be handled by Google TV having equivalent Android apps now, but I still like casting my local music from my phone to the TV when I'm reading. There's a $50 4K version out now, as well, if you have a higher resolution TV, but the TV I had the Chromecast plugged into caps out at 1080P, so, no need.