On LHR-SFO today, I was booked in 9A, and at boarding, in the GS lane, I was summoned and informed that the jump seat was broken and the FA had to use 9A as the nearest seat to the jump seat. I was offered the option of 10D, 10G, or 12G because here had been 3 no-shows, otherwise apparently it would have been down to Premium Plus. However I'd argue that it's legitimately a downgrade to go from a bulkhead straight window to a middle angled aisle. The obnoxious thought in my head was - why not ask the non-GS in 9L to move and move me to 9L!