Here, the seal plate has been damaged by excessive play in the journal bearings (also known as thrust bearings).
On the face of the plate, you can clearly see that the bore has been chewed and worn down by the bearings. On the rear of the plate, the bearings have also caused serious cracks to appear around the bore.
Damage like this allows oil to leak past the seal area and into the compressor side of the turbocharger. Apart from causing significant damage to the compressor, this will reduce the efficiency and effectiveness of the turbo, and quickly cause it to stop working at all.
Unfortunately, if your seal plate is damaged in this way, the only real solution is to replace the component and the bearings. Your turbo will also need to be fully cleaned to remove any oil.