Honestly, I'd say a lot of time there aren't any "legitimate sources" to prove the claims being made. That's a good chunk of the problem, because it seems that legitimate investigation and "linking" of said facts to prove the claims is next to
impossible without serious government-level powers of acquiring evidence. So inference needs to be used, unfortunately. And once you start inferring without direct evidence, you start sounding like a conspiracy theorist, which is now being used to shut-down dissent and questioning.
It's not like a journalist right now can tell Robinhood "give us all your internal emails so we can verify the reason you've stopped trading these stocks". Or "Hey Discord, let's look at your internal slack comms so we can figure out what evidence you had to conclude that the WSB chat rooms were filled with hatespeech." Or "give us a data-dump of all the users and comments you identified as hatespeech".
How about some regulation in that regard? Hey EU? Here's an idea for a possible scenario and how it could look:
1. Public company makes contentious claims.
2. Curious individual (maybe journalist) makes formal request for data to confirm.
3. By law, company above is obligated to provide access.
4. Individual gets given a secure-room, no-data-copying-allowed physical access to inspect and analyze said data.
5. Individual is allowed to report on said data.
Edit. Formatting.