Actual increase for an individual depends on many things. They also always seem to quote figures for the 'new pension' forgetting that anybody born before 1951 (ie most current pensioners) are on the old pension and get significantly less. I have not checked my figures but my increase was an awful lot less than £900.
As
@JamesT noted when it comes to the Old State Pension it's fiendishly complex but, boiling it down to its most simple, the weekly rate of the Old State Pension for 2022/23 was £141.85 and that increased to £156.20 for 2023/24 so an increase of £746.20 for the year. If that was a pensioners only income and they had no significant savings/capital (£10,000 or more) they would be able to access Pension Credit to top their income up so that their weekly income was at least £182.60 (2022/23) or £201.05 (2023/24) per week. Only a few quid less than the New State Pension and with passporting to things like 100% Council Tax Reduction, full Housing Benefit, free eye tests, NHS dental, etc.
But, the Old State Pension is a nightmare. Not sure I've ever seen someone who is getting exactly the basic rate!
Also interesting to compare what a working age person would have been getting around the same time. Standard Allowance for someone aged 25 or older under Universal Credit was £77.29 (2022/23) rising to £85.09 (2023/24) per week. An increase of £405.60 for the year and of course these people didn't get any Winter Fuel Payments either but were expected to cope...