What is the ultimate source of truth and who decides what that truth is...?

Today the Guardian wrote an article telling us that the EU accuses China of being behind Covid-19 disinformation campaigns:

So, here is the problem with fighting 'disinformation':

What is the ultimate source of truth and how do we know categorically that what that source is telling us can be trusted?

Is it because they run a government/block or because they own or control the mainstream or social media (that has the power to censor) that we should believe an accusation they make? What is the term for when governments and mainstream media themselves put out disinformation/misinformation...? We might call it propaganda, but they may call it 'News'. Ultimately it's all still disinformation and just because any of them say something is true, that doesn't mean it can be trusted. No Tech company, media magnate or Government is beyond reproach and to a large degree they service their own purposes in order to stay in power.

The mainstream and Government have been caught regularly trying to point to external sources as a problem, when in fact the truth might be closer to home, that more and more people are questioning the actions of their governments in what could be a manufactured crisis and which they, as the control system, are finding it harder and harder to manage and in turn to shut down free speech and concerns from their own citizens.

The European Commission said that Russia and China were running "targeted influence operations and disinformation campaigns in the EU, its neighbourhood, and globally". Seen another way, it could be said that the European Commission's own targeted influence and disinformation campaigns are no longer working in the EU, it's neighbourhood, and globally.

The Guardian is reporting here that French politicians were apparently furious when a Chinese website, in mid-April, reported that care workers had abandoned their jobs in the height of the Pandemic. But this is not untrue. Many care home workers had to self-isolate and were either unable to go to work or too afraid and this was especially the case in Spain. In the UK some care homes were greatly understaffed with staff opting to stay at home to protect themselves and care home residents as a precautionary action that may have been abused to varying degrees across care homes. Government and mainstream doesn't appear to have looked into whether there was a dereliction of duty involved.

So in summary what we may be seeing right now is an externalisation of the voices of free speech coming from the public being dressed up as disinformation/misinformation from abroad and in the case of China this seems to be about building up the rhetoric in support of some kind of retaliation in due course.

At this time in history when we still haven't seen the UK Government's reports on Russia, can we be entirely sure that those in power are not trying to twist and distort the truth for ulterior reasons? Never has it been more important to engage with our critical thinking and to see past the narratives. The question of what is true and what isn't is one that should remain pervasively with us at all times.