Er, what repositories to you have defined? Please check and share which files you have under /etc/apt/
AFAIK Ubuntu 20.04 did not ship with elasticsearch / kibana / logstash OOTB. So somehow you, or a predecessor, will have added them. Maybe you made/kept some documentation?
Overall, you seem a little lost. Software will updates itself if you tell it to do so, or sometimes it can even be default behavior, that you might typically disable. If you are running the commands above, you are instructing it to update software. It's not an accident. If you have not understood that, then that's on you really.
Please avoid expressions like "normal Linux updates", be more specific if you can, as that could can mean 101 things.
I've seen that normal Linux updates can indeed cause an "upgrade" to a newer ES and related component versions.
Er, yes, if you told it so.
8.10.0 / 8.6.1 / ... ? Perhaps you can search your log files here, when you upgrade packages via apt tools, that version upgrade is typically logged. I dont recall where in 20.04, in 24.04 I used this:
# PACKAGE="google-chrome" && { zcat /var/log/apt/term.log.1.gz ; cat /var/log/apt/term.log ; } | egrep "Log started|Unpacking ${PACKAGE}" | fgrep -C1 "${PACKAGE}"
Log started: 2025-01-03 20:57:44
Unpacking google-chrome-stable (131.0.6778.204-1) ...
Log started: 2025-01-03 20:58:22
--
Log started: 2025-01-17 17:45:02
Unpacking google-chrome-stable (132.0.6834.83-1) over (131.0.6778.204-1) ...
Log started: 2025-01-17 17:46:25
--
Log started: 2025-01-24 20:53:17
Unpacking google-chrome-stable (132.0.6834.110-1) over (132.0.6834.83-1) ...
Log started: 2025-01-26 00:00:56
--
Log started: 2025-01-30 16:06:12
Unpacking google-chrome-stable (132.0.6834.159-1) over (132.0.6834.110-1) ...
Log started: 2025-01-30 18:00:13
--
Log started: 2025-02-06 23:45:27
Unpacking google-chrome-stable (133.0.6943.53-1) over (132.0.6834.159-1) ...
Log started: 2025-02-07 23:42:20
showing (eg) when package google-chrome has been updated on my system. But typically those log files cycle very quickly.
Anyways, thats all a bit irrelevant, the point is to try to get you back to a working system, right? Output of
apt list | egrep '^(elasticsearch|kibana|logstash)'
on your various systems would maybe help. And we wont be able to help until you post the response to the curl requests @stephenb requested.