I have had the same problem on debian 11, after 1 year using, the system did not started because the hdd was 100 % full.
Now I use KDE-Neon, and I observe gradually that I will have the same problem as I had on Debian too.

It is those Updates I almost everyday have:
https://ibb.co/nR2TssC
after the Update I see usually the HDD is getting bigger.
https://ibb.co/ZxrwpRK = before update
https://ibb.co/4VZ1bbX = after the update


Question: what is happening during the update? I think the older software (chrome, thunderbird, etc...) would have been deinstalled
before an update is starting, is it not?

Should I manually deinstall a software before update?
What should I do to avoid that my HDD is getting bigger so fast?