Avoid ztx validation during IBD if height is less than latest checkpoint

src/main.cpp

@@ -1363,6 +1363,11 @@ bool ContextualCheckTransaction(int32_t slowflag,const CBlock *block, CBlockInde
                                 REJECT_INVALID, "bad-txns-invalid-script-data-for-coinbase-time-lock");
     }
 
+    // Avoid ztx validation during IBD if height is less than latest checkpoint
+    if (fCheckpointsEnabled && (nHeight < Checkpoints::GetTotalBlocksEstimate(Params().Checkpoints())) ) {
+        return true;
+    }
+
     if (!tx.vShieldedSpend.empty() ||
         !tx.vShieldedOutput.empty())
     {