This has been spoken about on here recently.
There's different rules for League 1 than the Championship. They more or less have a clean sheet to start with. The previous signings don't count as it was more about wages. From now it is something like a 3 year rolling amount of 39m losses. But I agree they have this season to do something but next season may well be different. There's a good chance they spent so much last year on transfers to take full advantage of the rules.
I'm pretty sure this is completely wrong.
Yes, transfer fees weren't included in the previous regulations therefore wouldn't have counted towards SCMP at the time.
However, with a wage bill that would've inevitably dwarfed the rest of L1's by some distance, their operational losses would've still been significant - especially as TV revenue drops by a sizeable amount as well. I would also imagine their wage bill now has further increased with the latest signings and the inevitable bonuses which they likely inserted into the contracts of marquee signings such as Stansfield last season.
It's not counted from now either. It doesn't just reset because they were relegated.