The minimum dot/bubble size in maps is too big and as a result visualisations are misleading as dots representing very different values can appear the same size (as discussed in the forum under "desk...
As part of our March update, we added a better sizing control that lets you adjust the size of the bubbles smaller so the range of values can be seen better. Read about this on our blog post: https://powerbi.microsoft.com/en-us/blog/power-bi-desktop-march-2019-feature-summary/#bubbleSize
