I have S-Pen from Samsung S21 and the S-Pen from Tab S9 they both look the same, what I want to tell you is that the one from S21 does not work in Tab S9. Unfortunately no concrete answer, but perhaps an impulse.

The S Pen gestures are only available on the Galaxy Z Fold5, Z Fold4, Fold3 5G, Galaxy S23 Ultra, S22 Ultra, S21 Ultra 5G, Galaxy Note20 series, Galaxy Note10 series, Galaxy Note10 Lite, Galaxy Tab S8 series, Tab S7 series, Galaxy Tab S7 FE and Galaxy Tab S6 that support One UI 3.1 or higher.

Unfortunately, we could not find out whether the replacement tips "Assy Acce-s Pen" are compatible with the Pen Tab S3: as long as the pen itself is the same brand, which I do not know. maybe a request to Samsung Support will help: https://www.samsung.com/ch...