Uneven inner tube when inflated inside the tyre
When installing an inner tube, one must take extra care with regard to the area near the valve stem.  It is fairly easy to get a portion of the thickened area around the stem "trapped" behind the tire bead, leading to a situation where the bead does not seat completely and resulting in a lump.

There are several strategies to deal with this.  First, make sure the tube is partly inflated (almost fully "puffed out") when you insert it into the tire and mount the tire.  Then, after the tire is (mostly) seated on the rim, let any excess pressure out of the tube and then press the stem in with your finger, about as far as you can get it to go.  This helps pull the rubber around the valve out from behind the tire bead.

Then, when you think you have it all together, carefully inspect the bead all the way around to make sure it's evenly seated to the rim everywhere.  Correct as needed.

I will note that if a tube is too large or too small you may get lumps, but your tube appears to be properly sized.