Some phone's don't allow the movement of any apps to a Sd Card.
If you go into Settings_Apps_Tap on the App you want to move to the Sd Card_Storage and tap change if that option is available.
If that option isn't there then your phone may not allow this function.
🌈 Stay Safe & Stay Alert. 🌈
Current Phone >Samsung Z Fold³ 5G.
Previous Phone > Note 20 Ultra 5G SM-N9860.
Ditto, same problem for me. I just purchased the phone and cannot find anything official from Samsung regarding this issue / limitation so I'll vote with my wallet and return the A21s and stick with my old phone compared to which the A21s proving to be a marginal upgrade.