Streaming throttling

Thanks for all your messages. I've walking around downtown Toronto with my wife, who has a Samsung, testing this thing. Youtube 4K or Twitch 1080 have terrible buffering everywhere around downtown Toronto, on 5G or LTE, on both our phones, whether in the app or in the browser. Youtube 1080p was acceptable but not what I would expect from Telus network. So it's not a phone or app issue. There was one random case though when we were inside a store with 2/4 bars of LTE reception - no buffering at all, lightning fast video rewinds.  

As I know, streaming videos even in 4K doesn't require much bandwidth. 25 mbps would be more than sufficient to have a decent viewing experience, and even LTE networks should be able to easily handle that. On my phone, speedtest shows 300/400+ mbps so I don't understand if it's all fake or what. But anyway, I believe that if Telus network wasn't good enough to handle 1080p Twitch streams, just in general the whole web browsing etc. experience on my phone would be unusable, but it's not, everything else is great. Just the video streaming has these weird issues, which leads me to believe that Telus purposely throttles video streaming speeds - unless there is another technical explanation I am not aware of, I am not a pro in the world of mobile networks. One of the main competitors seems to be doing that already - didn't test that myself but their 480p SD or 1080p HD streaming plans suggest they wouldn't allow customers to watch 4K content as well. But on Telus, I can't even watch a 1080p Twitch stream!

Tried calling customer support - waited for 30 min for someone to pick up, was redirected to a tech support team, waited for another 45 min, and just gave up. Maybe I'll try calling again but I don't think they can help.