I think it dates back to the 2020 primary campaign where she ran as a spoiler for the left. She rushed to be the first to declare candidacy, she tried to accuse Bernie Sanders* of defaming her and to cause a rift between her campaign and his, she stayed in the race when everyone else was dropping out, which was clearly a collusion to peel off voter share from Bernie while everyone else was endorsing Biden.

*Who then proceeded to not run in 2024, take a whole bunch of compromised positions especially on the first year of the Gaza extermination campaign, and do a few nothingburger "fighting oligarchy" rallies and tours that don't even attempt to leverage any power.

There are plenty more examples of Warren being disingenuous and flimsy on progressive positions. On consumer protections and anti-monopoly stances she's pretty good, but doesn't amount to more than a machine politician outside of that.

If someone is going to be a successful progressive politician, they'd better take principled socialist stances, stick to them, and fight for them. Otherwise we just get an endless string of Obamas who defise radical movements, triangulate with the Republicans, and eventually their entire legacy is overturned by the next Republican administration.

This is how "ratchet politics" works.