Re1 repeats how? Sometimes the computer will repeat in silly positions where human opponents won't.
The Berlin Defense is a solid way for black to play and that makes it annoying for white to push their advantage into a win. At the higher levels, this opening is drawish and so black often uses this to draw, whereas white wants to win, but it's difficult to prove a win. I share a bit more in this video (more from the black side, but also sharing ideas for white)
I was trying to analyze it with the engine end it seems that white can avoid the endgame and draw by repetition by just playing 5.Re1 instead of 5.d4
Am i wrong? If not, are there other reasons why the Berlin is so annoying for white and some plays 4.d3?