The number you don't know is how much the encoding workload grew in the time it took them to develop the system.
Let's use your numbers. Say that two years ago computing costs were $50M, and encoding was $46M of that. Now say that their costs are currently $100M, but the encoding workload grew 6X. Under the old system, that would have cost $276M, but under the new system it is on $22M. That would be a 92% savings, and would totally be in line given that in the last few years they have drastically increased their machine learning output, which would have overtaken encoding work.
Let's use your numbers. Say that two years ago computing costs were $50M, and encoding was $46M of that. Now say that their costs are currently $100M, but the encoding workload grew 6X. Under the old system, that would have cost $276M, but under the new system it is on $22M. That would be a 92% savings, and would totally be in line given that in the last few years they have drastically increased their machine learning output, which would have overtaken encoding work.