Since I also use SRL, I’ll have to throw in a slightly different viewpoint here:
I agree that the CTA is VERY annoying and destroying the experience when you are watching a Race on their Website, where multiple Streams are embedded so you can see who is ahead or behind - this is an enhanced experience you don’t get on Twitch!
However, the “basic” Discovery on the Main Page is, in my opinion exactly where the CTA and limited access/time in the Embed makes absolute sense: You discovered a streamer through the website - great! You had some time to check them out in that frame or reference and enjoyed it enough to stay for a while. It makes absolute sense to be redirected to Twitch for you to continue watching, especially since on SRL, you do not get Extensions, etc., which are part of “The Full Experience”, including the Panels of the streamer, where you can more often then not also find our more about them, including their Personal Best Times in Speedruns (usually).
You are missing out on these by watching on SRL instead of Twitch. You enjoyed their content for a while and should check out the experience the Runner intends for you to watch, not the reference frame SRL gives.
To complete this post with another opinion:
I myself do use SRL. I have had a very few people find me through it. I know that the SRL website is (sadly, relatively) poorly maintained with its fair share of issues. I most definitely want people to watch me on Twitch, not on SRL. I do use Extensions and know how my content appears on Twitch and that is the experience I want my viewers to have.
Edit/Afterhtought: I personally would prefer my viewers to get the CTA after 10 minutes, once or twice. Not in the form of the recurring purple screen - that one is disruptive. The dismissable modal i approve of in this very usecase.