Ok, so I've just checked the changes coming in. I assume the calculators will be updated soon to reflect the changes, but the one I linked definitely is still the existing payment schedule.
Right now loans are effectively "A 9% graduate tax on earnings above £27,295 for up to 30 years". The loans themselves are currently charged at interest rates above inflation, most people won't clear it.
Now it will be "A 9% graduate tax on earnings above £25,000 for up to 40 years". The interest rate will be lower as it will track with inflation. Most people won't clear it.
So yes - every single student who has loans will be disadvantaged by the change over all in the sense that it's still likely that most people won't ever clear it. So most people will end up paying it for 10 additional years.
I still 100% disagree that it disadvantages the poorest students, I was one of the poorest students and eligible for absolutely everything (grants, bursaries and loans). The vast majority of people I knew had the full amount of loans etc available to them regardless of their household income. And the middle income households were the students who struggled most through uni as their parents couldn't afford to make up the difference. The only students I knew who had no loans were international or absolutely loaded (and I mean absolutely loaded). So I expect this change will effect the vast majority of students equally and don't agree it singles out any one group at all.
I do however think that university funding and fees need a massive rethink though. We're struggling for nurses, midwives, teachers etc and they have no option but to go to university to do that job. I do think we should be incentivising courses that really are in demand and benefit us as a society.