I would expect 95%+ of TCP traffic to run on 22 (ssh), 25(smtp), 53(dns), 80(http), 443(https) plus another handful of lower than 1000 ports. Even common dev ports (3000,5000,8080) are below 9000. I don't think that's much different for UDP. Even most games probably rely on something <10,000.
It is, because of the way that UDP is typically used for different applications than TCP. While there are a few old, well known TCP/UDP pairs like 53, UDP is more often used with a dynamic port assignment scheme sometimes with a coordinating TCP protocol - such as SIP/RTP for VoIP that uses >16k, WebRTC, etc. A lot of games uses ports above 10k.
https://help.generationesports.com/hc/en-us/articles/3600611...
Besides games, I think many AV things, including VOIP and perhaps WebRTC (definitely UDP, less sure about port number). Possibly also HTTP/3; the server picks the UDP port number IIUC.
That's the preferred protocol for ultra-real-time games because a few ms ago is not helpful information to spend time recovering. A sufficiently fast-moving MMO could apply
Anything with real time communications like an FPS would use UDP as stale action data is mostly useless. The latest state of is all that matters.
Most such games will either layer their own streaming channel atop UDP for guaranteed ordered delivery of important messages or use a separate TCP socket as well.
You must not be looking very hard, pretty much every game engine uses UDP as the network transport. There are some notable exceptions like Java Minecraft.
MMOs often have TCP connections for things like chat and services like auction house (often even HTTP microservices), but most of the gameplay is still UDP.