No, the ProGrade Digital CFexpress Type B Gold 128GB is not compatible with the Sony FX3.
ProGrade CFexpress Type B cannot seat in the Sony FX3's Type A slot. Physical form-factor incompatibility.
What works instead
See all compatible memory card for the ProGrade Digital CFexpress Type B Gold 128GB →“This camera supports CFexpress Type A memory cards and SD memory cards”
“CFexpress Type B 1700 Gold Memory Card | ProGrade Digital”
Last verified:
Confidence: inferred