Seal large gap between sewage pipe and brick wall

Hello everyone,

what is the best way to seal the large gaps between the sewage pipes and the brick walls? During the brickwork, large areas were left open where a sewage pipe is now located. And at every second brick, you can see completely through the wall because cutting the stone there was too complicated. It is in the partition wall in the basement. Can you simply "fill" it layer by layer with mortar, or how is this normally done? Thank you very much

There is particle board that is plastered.