Why did the universal connectivity charge increase from .68 to $3.18 from April to May?

I was incorrectly charged $10 for the Canada/Mexico calling plan. The agent gave me a $10 credit to address this; however the bill that the charge and credit appears on dated 5/20/22 has higher taxes/fees. The UCC is just one, but it went from about $.70 to over $3 from one month to the next.

I chatted with a Xfinity Mobile representative who couldn't explain if the fees/taxes increased a lot from one month to the next. I asked for a supervisor and was told they aren't available in the evenings. 

Not good service, but hoping someone can explain.