Plus also there's something fishy about how much actually gets donated. They donate only the profits of each single to charity, and looking at their records on companies house. Having had a few records signed, most of the contracts will assume high levels of costs to extract the cash early on during the agreement, with royalties (profits) only paid out after costs have been taken into consideration.
Someone has worked out that they've only donated £350k over the 4 years so far, which would assume that they have allegedly significant costs before the Trussell Trust get anything.
It also wouldn't surprise me that they're bank rolling purchases/streaming of the song via just to get it to number one as well. Spotify only has it at half a million streams so far.