Regardless of the environment you should see a similar entry to this one in the Azure B2C (not users node) Audit logs:
Activity
Date : 2020-08-05T22:03:43.2050414+00:00
Name : Issue an id_token to the application
CorrelationId : 1ec217b4-7dda-4489-9708-bd0cead14e4b
Category : B2C
Activity Status
Status : Success
Reason : N/A
Initiated by (actor)
Type : Application
ObjectId : 810fb912-a758-4409-af18-dbfc56b0b3ee
Spn : f348b410-cec6-45bd-9fcd-b61cdeebd5fc
Target(s)
Target
Type : User
ObjectId : c806ae48-56df-4d71-adab-efb16f425454
Additional Details
TenantId : AlfredoIDCxPB2C.onmicrosoft.com
PolicyId : B2C_1_SignInSignUp
ApplicationId : f348b410-cec6-45bd-9fcd-b61cdeebd5fc
Client : Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.38 Safari/537.36 Edg/85.0.564.18
ClientIpAddress : 190.234.149.167