Ubuntu's trust problem in 4 concrete issues - verified facts, no FUD
Strong agree. I use a derivative that blocks snaps instead of direct Kubuntu now, and it wasn’t Just because of the snaps.

I use a derivative

Without Ubuntu Pro subscription the entire Universe repository does not receive any security updates by Canonical:

canonical.com/…/ubuntu-pro-enhanced-security-and-…

You should consider switching to an entirely independent distribution that does not lock security updates behind a paywall, perhaps something based directly on Debian or Fedora.

How Ubuntu Pro delivers enhanced security and manageability for Linux Desktop users | Canonical

This week Ubuntu Pro entered general availability, giving Ubuntu users access to expanded security coverage on top of key enterprise management features. […]

Canonical
What’s a better alternative that uses apt and KDE and has relatively up-to-date packages (other than Debian testing)?

Fedora offers apt. AFAIK not by default, so it has to be installed via dnf first but then it’s available.

It’s been like that for years.

https://www.google.com/search?q=why+shouldn%27t+you+use+apt+on+fedora&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari&safe=active

It’s a really bad idea to have two package managers overlap (this is also why more “cross-system” package managers like nix and brew are okay: they consciously install to separate paths to avoid overlapping)

Fedora does not offer APT repositories, so if you somehow don’t overlap and pretty much exclusively use APT, you’re pretty much just converting your distro to Debian (or whatever’s providing your repos). In the forums we call this a Frankenstein; support is seldom given for raising the dead.

Before you continue to Google Search

www.google.com/search?q=why+shouldn't+you+use+apt…

Is your answer whatever Gemini happens to hallucinate on a given day?

Before you continue to Google Search