If you have secrets anywhere near your live stream, it's not a question if "if" you will leak them but "when." Don't put yourself in that situation.
Work _hard_ to keep yourself out of that situation.
I’d assume you’re not coding on a production system so your secrets shouldn’t be too hard to revoke, cycle them after your stream and any time you leak them.
I generate my secrets once, send them off to the secrets service, and then my service queries that service. I never see the secrets with my own eyes.
I've not come across what you describe
Let's say I live streamed implementing Stripe. There's no way to avoid not showing my test API keys if I'm going to show the end to end process of setting everything up. The best I could do is to roll the keys before I start the stream but this degrades the quality of the stream since it's not from scratch.
Of course those keys and anything else that's sensitive would be sitting in an .env file, and I'd also have an .env.example file showing how it's set up without anything sensitive being in there (I do this already in my pre-recorded videos). Even going as far as preventing the real .env file coming up when I fuzzy open files so I don't open it by accident and the contents of that file being ignored from multi-file searches.
If you revealed a Stripe key only to change it 1 minute afterwards, you still need a process to change it in secret, which goes back to my original reply of setting up a dedicated "secret" scene so you can modify things in private.
You are making the choice to live stream. It is always possible to avoid live streaming. Always.