If they obtained info about this through their role as a senator/congressperson, and not just through normal channels. If I understand it correctly:
Insider trading off of classified or whatever info they get from their senate/congress job - not illegal (though imo it should be illegal). (Edit: as mandevil points out, strictly speaking illegal, but largely uneforceable/unenforced)
Insider trading off of info they got from their buddy at XYZ place who knew about something ahead of time, unrelated to their senate/congress job - still illegal, same as for other people.
Why don’t people track the investments of senators and congresspeople and race to follow them? It seems like an easy way to get nearly insider trading.
This is false. Then-sitting Congressman Chris Collins (R-NY) pled guilty and was sentenced to 26 months in prison for insider-trading back in 2019-2020. He was pardoned by President Donald Trump as one of his last official acts as President, but Collins still spent 10 weeks in prison for insider-trading as a sitting congressman (this was for knowledge he gained outside of his duties as a congressman, it was knowledge he got as a member of the Board of a company).
Congresspersons separately aren't allowed to trade on things they learn from their job- that was banned in 2012 under the STOCK act.
Eh, my take is that the electronic disclosure stuff makes this more annoying for the activists- the people who are building dashboards of Congressional performance etc.- but doesn't fundamentally change the nature of the problem. The activists still build their dashboards, still comb through the documents and find things that look really bad, it's just slightly more out of date and slightly more work for them.
I do think that something like the Ban Congressional Stock Trading Act (everything in a blind trust), or its even more draconian (no blind trusts, just sell!) Ban Stock Trading for Government Officials Act will probably pass, eventually. Those are general markers for where we are going. But to just say "It's not illegal if you are a Member of Congress" is flat wrong and encourages a level of cynicism that makes it harder to actually fix the problems we face today.
Insider trading off of classified or whatever info they get from their senate/congress job - not illegal (though imo it should be illegal). (Edit: as mandevil points out, strictly speaking illegal, but largely uneforceable/unenforced)
Insider trading off of info they got from their buddy at XYZ place who knew about something ahead of time, unrelated to their senate/congress job - still illegal, same as for other people.