Found these comments on Reddit.
"SciresM
As someone who does know what he's talking about (I wrote the write-up on the early model vulnerability he mentions), all Switches up through System Version 3.0.2 will be softmoddable -- and those interested in softmodding on 4.1.0 should not update to any newer firmwares, because in the long run those will be supported too."
"ThuMuffinMAN
Hello, please link me to video of a Switch softmodded on newer firmware thank you."
"SciresM
I hope that you find this sufficient:
"
"SciresM
I am extremely confident I understand TrustZone's attack surface. When I say I can't think of any mechanism, I mean that any TrustZone bug affecting 3.0.1 will necessarily affect 4.1.0, because I understand the set of patches between those versions."