Your ping will show a higher number than it did around Season 10, because that’s exactly when the developers changed the RTT and Ping stats to one value called Latency (LAT). More info on that here: Replacing Ping and RTT with Latency
The reason you’re being connected to South America is because that’s where the game sees the best ping for you to play. Sometimes ISPs change their routing and that can add extra latency when trying to reach the Los Angeles or Chicago datacenters. You might be able to use a free VPN to make it look like your connection is coming from within the states those servers are located in, which will force you to connect to them. But there’s no official support for VPNs (like how to set them up, etc) on the forum.