I am incredibly grateful that @rk and I had a chance to speak at Black Hat and DEF CON this year (https://i.blackhat.com/BH-US-24/Presentations/REVISED02-US24_Moore_Secure_Shells_in_Shambles_Wednesday.pdf).
Even after 20+ years of speaking at security conferences the entire process is anxiety-inducing, and nothing ever seems cool enough to share with the community. I've had two other talks rejected this year (BSidesLV & a public sector event) and I agree with their reasoning. I'm also excited to keynote LASCON (https://lascon.org/) and hoping to get accepted for JawnCon (https://www.jawncon.org/). I love that our community cares about the quality and appropriateness of a submission over favoritism to (what must now be) the "old guard".
If you have something unique to share with the world, please do so, and don't let the rejections keep you from continuing to apply to CFPs. A great resource for upcoming conferences is CFP Time: https://www.cfptime.org/home