According to the support page I linked, SMBv1 is not installed by default when installing Windows 10 Version 1709 and up, and also uninstalls itself it it hasn't been used within 15 days(if you already have it installed before upgrading). However, SMBv1 can be reinstalled if it is uninstalled.
The MicroSD Management app present on the 3DS uses SMBv1, so it is affected by the issue.