I've been on just over £70k for most of the last 5 years. If you had been on £70k during that time, your actual tax / NI paid has gone down, and bands have slowly lifted and NI contributions have changed. Yes, inflation means that for most this isn't a huge help, but tax on £70k has dropped by just under 2k during that time.
Its also worth reminding yourself where £45k puts you. The 'median disposable household income', which means the amount of money a household has after tax, including benefits, is £41k. That's about £52k for a single person. Student loans don't count.
So they're flying a flag about something which will affect the higher-earning half of the country. Undoing the rather cynical drop in employee NICs introduced in 2024, for higher rate tax payers only or adding 1% point to the higher rate tax would affect less than half the country by not very much. On £70k, well above the median, that last would be an extra £200 a year.
I don't know, but an extra £200 a year won't make me stop working any time soon any more than the £300 or so I got extra out of the NIC reductions in 2024 encouraged me to vote tory.