eBay requires products in the following categories to specify a grading in the product condition section and provide relevant information in the item details:

Non-Sport Trading Card Singles (183050)
CCG Individual Cards (183454)
Sports Trading Card Singles (261328)

If the item condition is Graded, you need to add "Professional Grader" to the item specification.
If the Grade is not specified, Soldeazy will use eBay's default value for successful listing:
Grader: Professional Sports Authenticator (PSA)
Grade: 10

If the item condition is Ungraded, you need to add the following to the item specification: Card Condition.
If it is not specified in datasheet, SoldEazy will use the default value for successful listing:
Card Condition: Near mint or better.