diff --git a/pgxn/neon/walproposer_pg.c b/pgxn/neon/walproposer_pg.c
index 874a1590ac..b0f5828d39 100644
--- a/pgxn/neon/walproposer_pg.c
+++ b/pgxn/neon/walproposer_pg.c
@@ -507,19 +507,45 @@ backpressure_lag_impl(void)
 			 LSN_FORMAT_ARGS(flushPtr),
 			 LSN_FORMAT_ARGS(applyPtr));
 
-		if ((writePtr != InvalidXLogRecPtr && max_replication_write_lag > 0 && myFlushLsn > writePtr + max_replication_write_lag * MB))
+		if (lakebase_mode)
 		{
-			return (myFlushLsn - writePtr - max_replication_write_lag * MB);
-		}
+			// in case PG does not have shard map initialized, we assume PG always has 1 shard at minimum.
+			shardno_t num_shards = Max(1, get_num_shards());
+			int tenant_max_replication_apply_lag = num_shards * max_replication_apply_lag;
+			int tenant_max_replication_flush_lag = num_shards * max_replication_flush_lag;
+			int tenant_max_replication_write_lag = num_shards * max_replication_write_lag;
 
-		if ((flushPtr != InvalidXLogRecPtr && max_replication_flush_lag > 0 && myFlushLsn > flushPtr + max_replication_flush_lag * MB))
-		{
-			return (myFlushLsn - flushPtr - max_replication_flush_lag * MB);
-		}
+			if ((writePtr != InvalidXLogRecPtr && tenant_max_replication_write_lag > 0 && myFlushLsn > writePtr + tenant_max_replication_write_lag * MB))
+			{
+				return (myFlushLsn - writePtr - tenant_max_replication_write_lag * MB);
+			}
 
-		if ((applyPtr != InvalidXLogRecPtr && max_replication_apply_lag > 0 && myFlushLsn > applyPtr + max_replication_apply_lag * MB))
+			if ((flushPtr != InvalidXLogRecPtr && tenant_max_replication_flush_lag > 0 && myFlushLsn > flushPtr + tenant_max_replication_flush_lag * MB))
+			{
+				return (myFlushLsn - flushPtr - tenant_max_replication_flush_lag * MB);
+			}
+
+			if ((applyPtr != InvalidXLogRecPtr && tenant_max_replication_apply_lag > 0 && myFlushLsn > applyPtr + tenant_max_replication_apply_lag * MB))
+			{
+				return (myFlushLsn - applyPtr - tenant_max_replication_apply_lag * MB);
+			}
+		}
+		else
 		{
-			return (myFlushLsn - applyPtr - max_replication_apply_lag * MB);
+			if ((writePtr != InvalidXLogRecPtr && max_replication_write_lag > 0 && myFlushLsn > writePtr + max_replication_write_lag * MB))
+			{
+				return (myFlushLsn - writePtr - max_replication_write_lag * MB);
+			}
+
+			if ((flushPtr != InvalidXLogRecPtr && max_replication_flush_lag > 0 && myFlushLsn > flushPtr + max_replication_flush_lag * MB))
+			{
+				return (myFlushLsn - flushPtr - max_replication_flush_lag * MB);
+			}
+
+			if ((applyPtr != InvalidXLogRecPtr && max_replication_apply_lag > 0 && myFlushLsn > applyPtr + max_replication_apply_lag * MB))
+			{
+				return (myFlushLsn - applyPtr - max_replication_apply_lag * MB);
+			}
 		}
 	}
 	return 0;
diff --git a/test_runner/regress/test_sharding.py b/test_runner/regress/test_sharding.py
index c2907d8a4f..4e46b67988 100644
--- a/test_runner/regress/test_sharding.py
+++ b/test_runner/regress/test_sharding.py
@@ -1751,14 +1751,15 @@ def test_back_pressure_per_shard(neon_env_builder: NeonEnvBuilder):
             "max_replication_apply_lag = 0",
             "max_replication_flush_lag = 15MB",
             "neon.max_cluster_size = 10GB",
+            "neon.lakebase_mode = true",
         ],
     )
     endpoint.respec(skip_pg_catalog_updates=False)
     endpoint.start()
 
-    # generate 10MB of data
+    # generate 20MB of data
     endpoint.safe_psql(
-        "CREATE TABLE usertable AS SELECT s AS KEY, repeat('a', 1000) as VALUE from generate_series(1, 10000) s;"
+        "CREATE TABLE usertable AS SELECT s AS KEY, repeat('a', 1000) as VALUE from generate_series(1, 20000) s;"
     )
     res = endpoint.safe_psql("SELECT neon.backpressure_throttling_time() as throttling_time")[0]
     assert res[0] == 0, f"throttling_time should be 0, but got {res[0]}"