There were also cancellations announced by SWR» to SE services, which sounds odd. They are borrowing a platform (21, currently) for a week, accessed via the Nine Elms Flyover, or in other words by playing at being Eurostars.
P21 and P22 was planned for SE. I think what has been happening is that if disruption to the wider SWR service is forecast, then they are being pre-emptively diverted to Blackfriars. Lose access to a main line (whether DMF, UMF, UMR) in the station throat and the knock on effects ripple across the other 5 lines.
The fact that Blackfriars appears to have spare capacity to take that 2 tph service anyway is intriguing, it is as if the four days planned at Waterloo was only being done to create a precedent for future use?
There seems to be a greater emphasis on normal "run of the mill" random faults at the moment.
AIUI▸ no recent modifications were made to the platform lines on the Windsor side and in the middle of the array of platforms used by main fast trains. It stands to reason that there will be a minor fault every few days or weeks, it has always been so.
Paul