I very much doubt that any genuinely overpaid good citizens will use it to admit their error - and in any event they would be ill-advised to. If they think they are in that position, they should deal with it in advance of filing SA100.
What I fear will happen, though, is that those who were in doubt about the much-discussed inadequate and confusing wording of SEISS round 3, will now revisit their doubt, only this time with the benefit of hindsight about how their profits turned out. This may lead them to re-apply the test of their "reasonable belief" at the time of their application, only this time viewed from the later perspective and with the benefit of hindsight.
I am concerned that this will lead people, especially if not professionaly advised, to conclude that they claimed SEISS R3 "incorrectly" when in fact they did no such thing. They may overlook the pivotal point that their reasonable belief at the time of the application was what mattered.
I think it is very unfair to include this section and some taxpayers will be unfairly penalised. I hope advisers will give very robust and precise advice to any clients who consult them about this.