This is due to the Sampling Point Size (165) to Padding (6) ratio being too small for the material property values you are using.
The solution is to update the font asset to increase this ratio. A good starting value is like 10%. See the following FAQ Question 2 and 10 from this sticky thread and post for more details.
P.S. A sampling point size of 165 is pretty large and may not be necessary. I would suggest using the default Sampling Point Size of 90 with Padding of 9 for a Ratio of 10%.