Steps to reproduce:

Using the release file instructed in the download page:

markku@repotest:~$ wget https://repo.zabbix.com/zabbix/8.0/release/debian/pool/main/z/zabbix-release/zabbix-release_latest_8.0+debian13_all.deb
...

2026-11-07 16:17:25 (335 MB/s) - ‘zabbix-release_latest_8.0+debian13_all.deb’ saved [8648/8648]

markku@repotest:~$ sudo dpkg -i zabbix-release_latest_8.0+debian13_all.deb
Selecting previously unselected package zabbix-release.
(Reading database ... 46110 files and directories currently installed.)
Preparing to unpack zabbix-release_latest_8.0+debian13_all.deb ...
Unpacking zabbix-release (1:8.0-0.5+debian13) ...
Setting up zabbix-release (1:8.0-0.5+debian13) ...
markku@repotest:~$ sudo apt update
Hit:1 http://deb.debian.org/debian trixie InRelease
Hit:2 http://deb.debian.org/debian trixie-updates InRelease
Hit:3 http://security.debian.org/debian-security trixie-security InRelease
Get:4 https://repo.zabbix.com/zabbix/8.0/release/debian trixie InRelease [2,460 B]
Get:5 https://repo.zabbix.com/zabbix-tools/debian-ubuntu trixie InRelease [2,474 B]
Get:6 https://repo.zabbix.com/zabbix/8.0/stable/debian trixie InRelease [3,918 B]
Get:7 https://repo.zabbix.com/zabbix/8.0/release/debian trixie/main Sources [1,348 B]
Get:8 https://repo.zabbix.com/zabbix/8.0/release/debian trixie/main all Packages [843 B]
Get:9 https://repo.zabbix.com/zabbix-tools/debian-ubuntu trixie/main Sources [1,571 B]
Get:10 https://repo.zabbix.com/zabbix-tools/debian-ubuntu trixie/main all Packages [969 B]
Get:11 https://repo.zabbix.com/zabbix/8.0/stable/debian trixie/main Sources [3,288 B]
Get:12 https://repo.zabbix.com/zabbix/8.0/stable/debian trixie/main amd64 Packages [5,347 B]
Get:13 https://repo.zabbix.com/zabbix/8.0/stable/debian trixie/main all Packages [1,407 B]
Fetched 23.6 kB in 2s (15.5 kB/s)
1 package can be upgraded. Run 'apt list --upgradable' to see it.
markku@repotest:~$ sudo apt list --upgradable
zabbix-release/unknown 2:8.0-0.3+debian13 all [upgradable from: 1:8.0-0.5+debian13]
Notice: There are 4 additional versions. Please use the '-a' switch to see them.
markku@repotest:~$

Expected:

The zabbix-release is the latest one and not needing an update right away.