Me same. I'm on ubuntu since 16.04 and it's annoying switching, because I'm used to it so much. Definitely switching on Debian, because they're not shipping software through apt anymore (eg. browsers). I'm running that through nix right now, and I don't want to deal with this nonsense.
I was thinking of just going entirely to Nix. The last time I tried it was 2021 (on a dual boot where I also tried Arch cause my colleague was bemoaning my Ubuntu usage). Yeah, it is annoying having to look up how to configure things the Nix way, but it all makes sense and it stems from the fact every application does it 'their way'.
Either way, I just wanted to note you can use APT to include Mozilla's Firefox and Thunderbird repo. That way, you get a .deb from them.
One specific thing I like about Ubuntu: I know a new version gets released every six months (I believe OpenBSD innovated this?) and the version is recognized by date. The LTS is released every two years around april in the even years. Otherwise it is april/october.
> it's annoying switching, because I'm used to it so much
Since you're switching to Debian, could you tell me what you don't understand in Debian that was working fine on Ubuntu for you?
I am not an Ubuntu user, so it's hard for me to know. But I find it very surprising that after 10 years on Ubuntu, it would be "annoying" to switch to Debian.