This hit the early morning BBC Radio news yesterday.
Mixture of flexible working and “reduction in force”. UK commercial leases tend to be 25 years without break clauses (but generally allowed to sublet which is the usual exit for excess space).
“Threads” (Meta’s competitor to “X”) also recently launched in the UK and has gained more traction that other twitter competitors such as Mastodon
The FB offices are very much a premium/trophy office/location.
(I know this part of London well; about 30 years ago when I worked for Logica, I worked in a building nearby to this one, before this was all redeveloped, including accessing the roof to help an engineer set up a special sat dish needed for TV set top box development work I was doing at the time–and having to deal with microwave interference from nearby BT Tower, when it was actually a key part of UK telephone network)