A lot of the rail replacement currently is due to staff sickness ... Covid has hit a lot of things very badly.
Positively, the government has heavily supported rail through the pandemic. (estimated 22 billion pounds in 2020-21, up from 11 billion in 2019-20) (1)
Mostly to make up for loss of passenger ticket income.
Investment in High Speed 2 is also continuing despite the current situation, which I'm relatively hopeful about.
On the other hand the government has demanded cutbacks on operations to possibly 80% or less of pre-covid, and there seems to be a lot of overcrowding in some areas where the demand has rebounded faster. There is also a fairly widespread withdrawal of much of the onboard catering :-(
(1) https://assets.publishing.service.gov.uk/government/uploads/...