Hello,
the size of tag label
--
depicts the RELATIVE number of items associated with the tags
... so in your case you see this
because your 3 tags are associated with a single item each thus they get THE SAME small font ...
NOTE: that if you have some tags with about 100 items associated, then you may get a very small font or a very big font depending on ... read below
-- These tags will get a large font if maximum associated items for any tag is e.g. 120
but if you have some tags that are associated with 1000 items, then your tags that are associated with about 100 items will get a rather small font.
in short what you see is normal , and once you add more tags associations with different number items associated with different tag then you will see different fonts ...
Regards