I've tried the following applications:
- Firefox (Snap)
- Vivaldi (DEB)
- Edge (Flatpak)
I put the root and immediate certificate crt files in /usr/local/share/ca-certificates/, and ran update-ca-certificates, and no dice. I did try to manually import on my Firefox (snap) using the same certificates and that worked.
Edge (Flatpak) on my Rocky Linux 9 works fine when I do update-ca-trust using the same certificates.
The only difference between the one in RL9 & Ubuntu is that I had to split one of the certificates in Ubuntu due to it skipping, but otherwise, they're the same.