Consumer-grade Wi-Fi is also a major problem when it comes to latency & jitter. It doesn't even have to be game streaming, any real-time application such as calls suffer from it as well, despite not actually requiring much bandwidth at all.

Unfortunately there is no user-friendly tool to test for this. Most tests focus purely on speed, which can be tricked by various packet-loss-compensation algorithms, so you can score a "perfect" 1Gbps speedtest despite the connection cutting completely for a second.