Read the "value" being redeemed in a Bitcoin P2SH Script Is there any way for a Bitcoin P2SH Script to read the amount of Satoshis being redeemed?
Inputs do not reference the value of the UTXO they spend. You need to look up the spent UTXO to find the value. Usually, this information is available to a node via the UTXO set, or can be looked up by inspecting the transaction that created the UTXO.