In Garmin Connect, the y-axis for swimming pace is inverted. The faster your pace (ie. the lower the number of seconds per 100m), the higher the bar on the graph.
At the same time, SWOLF has a normal y-axis. The higher (ie. the worse) your SWOLF value, the higher the bar.
This can be confusing especially when overlaying the pace with the SWOLF value. For a good pace, you are looking for a high bar, but for a good SWOLF rating, you are looking for a low bar.
My suggestion would be to invert the SWOLF axis. The lower, which means better, you SWOLF, the higher the bar on the graph should be.