Maybe? It depends what Timeshift was monitoring/backing up. In any case, the tool you used to generate the keys I believe has the ability to delete the keys (they’re just files on your system). Look up the documentation to be sure. It’s been a hot minute since I mucked around with Secure Boot, and it’s not strictly required, so I just gave up.
That’s about the extent of my secure boot knowledge. I do hope more knowledgeable people have better advice for you!
Yes, but Coffee Stain is Swedish, and they’re the publisher. Maybe they can get a sign that’s half the dimensions of the others…?