tighter limit

The default block gas limit can fit 1523 txs
Each Tx adds an 8-byte of length prefix.
50K is enoguh to add 1523 times 8 bytes and still stay in an L2 message

execution/gethexec/sequencer.go

@@ -111,7 +111,7 @@ func (c *SequencerConfig) Validate() error {
 	if c.expectedSurplusSoftThreshold < c.expectedSurplusHardThreshold {
 		return errors.New("expected-surplus-soft-threshold cannot be lower than expected-surplus-hard-threshold")
 	}
-	if c.MaxTxDataSize > arbostypes.MaxL2MessageSize-10000 {
+	if c.MaxTxDataSize > arbostypes.MaxL2MessageSize-50000 {
 		return errors.New("max-tx-data-size too large for MaxL2MessageSize")
 	}
 	return nil