TL;DR there was a backdoor found in the XZ program. All major distros have been updated but it is recommended that you do a fresh install on systems that are exposed to the internet and that had the bad version of the program. Only upstream distros were affected.
And I don’t think you understand OPs point. Of course you should be paranoid as a person like that, but most users aren’t targets. If you, as a regular user, get this paranoid about using computers, maybe you should evaluate your priorities.
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