I would say the reason for the bulge is a problem with the niche, it runs out of level from the bottom to the top...
The tell tale sign is this joint getting wider as he is trying to bend the tile back to meet the wall..
This could be down to poor construction of the niche and surrounding wall or the plastering.
Some mosaic can be all over the place and out of line on the mesh..
Having said that, you should never leave a job like that, you just cut through the mesh and realine them.
The metal trims should be mitred too..
All in all the job looks rushed to me, not done by a skilled tiler more a general handy man...
The tell tale sign is this joint getting wider as he is trying to bend the tile back to meet the wall..
This could be down to poor construction of the niche and surrounding wall or the plastering.
Some mosaic can be all over the place and out of line on the mesh..
Having said that, you should never leave a job like that, you just cut through the mesh and realine them.
The metal trims should be mitred too..
All in all the job looks rushed to me, not done by a skilled tiler more a general handy man...