A Dutch national who resides in the UK through the settlement scheme can continue to use a Dutch national ID card to enter the UK. There are a few other fairly uncommon circumstances in which a Dutch national ID card may be used. For everyone else, a passport is necessary.
See https://www.gov.uk/uk-border-control/before-you-leave-for-the-uk:
You cannot use a national identity card from an EU country, Switzerland, Norway, Iceland or Liechtenstein to enter the UK unless you:
- have settled or pre-settled status under the EU Settlement Scheme, or Jersey, Guernsey or the Isle of Man’s settlement schemes
- have an EU Settlement Scheme family permit, or the equivalent from Jersey, Guernsey or the Isle of Man
- have a Frontier Worker permit
- are an S2 Healthcare Visitor
- are a Swiss national and have a Service Provider from Switzerland visa
The underlying logic here is that passports are generally required, but use of a national ID card is part of the right of free movement that is preserved after Brexit for certain people who were exercising the right at the time of the UK's withdrawal from the EU.
(The Swiss Service Provider provision will be related to a free movement of services agreement between Switzerland and the EU, or perhaps between Switzerland and the UK, but I do not know the details; I only included it in the quotation for the sake of completeness.)