Unable to upgrade to 21.04 from Kubuntu 20.10

[JORGETECH]

I tried removing the kubuntu-backports PPA and some other third-party stuff I had installed but the problem still persists, apt complains about some packages, most of them are KDE related ones.

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: ubuntu-release-upgrader-core 1:20.10.16
ProcVersionSignature: Ubuntu 5.8.0-55.62-generic 5.8.18
Uname: Linux 5.8.0-55-generic x86_64
ApportVersion: 2.20.11-0ubuntu50.7
Architecture: amd64
CasperMD5CheckResult: skip
CrashDB: ubuntu
CurrentDesktop: KDE
Date: Sun Jun 6 18:49:06 2021
InstallationDate: Installed on 2018-09-30 (980 days ago)
InstallationMedia: Kubuntu 18.10 "Cosmic Cuttlefish" - Beta amd64 (20180927)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to groovy on 2021-06-06 (0 days ago)
VarLogDistupgradeTermlog: