Hi, Poloniex was a Big one, but lately very few people use it. Most of the people from US run the bot on Binance.us and Coinbase.com. Usually the most popular exchanges get more love from dev team. Anyway, v21.1 works pretty good on Poloniex. You can download latest stable versions, like v21.1 from this link:
https://gunbot.shop/category/downloads/