The reports that these incels have been sending do not contain enough specific information to be useful to the irs. Proof that a person is a sex worker is not proof that they don't pay taxes. The chance that any report of her online social media account results in an audit by the irs is minuscule to non-existent. These reports are most often used by jealous ex lovers to report their ex's, they have much more detailed information than these trolls do but rarely enough anyway to actually do any good. The main purpose of reporting a sex worker is to scare her, if they actually cared about her paying taxes they would not inform the reportee and give them a chance to cover their tracks. Any near term panic is fairly pointless anyway, it can take years for the IRS to get around to responding to a tax fraud case. If they do so, by the way, it will always be by mail.
The bigger worry is if she's been depositing the money into a bank account, if she deposits enough it can trigger an automatic report. Often the irs doesn't have the time or resources to pursue small time fraud but if she's been making a lot of money she may get hit with the audit lottery. If so the process has probably been working its way through the beurocracy for years now.
Tell her anyway to utilize her fifth amendment rights and cease admitting her guilt in this case through any communication channel. Only do that to a lawyer that she has personally hired. Definitely not over messaging services which store a permanent record, or on social media. What the trolls possibly spammed to the irs is not proof of anything, an admission of guilt publicly or through private channels that could be subpeonad definitely is. There is zero personal good that can come to her from failing to exercise her rights in this regard.
In the unlikely event that she is contacted by the irs, do not confirm or deny anything without first speaking to a lawyer. Tell her to look up online (there are resources for sex workers that can aid in this) how to file the appropriate tax forms, and begin paying all taxes owed. Take no other action, unless she is contacted by the irs. In which case she should take the actions that the lawyer directed her to take.