CDK forward-deploying resource from another stack

We have our own library (.NET) of L3 constructs for quickly deploying a playbook of resources. One of them a composite arrangement of ASG, ALB, with options for CloudFront, WAF, public HTTP API Gateway, etc. A CodePipeline process feeds application binaries to the ASG instances. This construct type is meant to be deployed as part of an application layer stack, which has dependency on a base stack that covers the fundamental infrastructure resources like VPC, security groups, S3 buckets, etc.

Yesterday on running cdk diff and deploy of the base stack of a new system environment, I noticed the VPC link of the API Gateway AWS::ApiGatewayV2::VpcLink of the above-mentioned construct has somehow found its way into the template of the base stack instead of the yet-to-be-deployed application stack.

[+] AWS::EC2::Subnet SYSTEM-vpc-ENVIRONMENT/vpc/cacheSubnet3/Subnet SYSTEMvpcENVIRONMENTvpccacheSubnet3SubnetC364FB30
[+] AWS::EC2::RouteTable SYSTEM-vpc-ENVIRONMENT/vpc/cacheSubnet3/RouteTable SYSTEMvpcENVIRONMENTvpccacheSubnet3RouteTableFB233B7C
[+] AWS::EC2::SubnetRouteTableAssociation SYSTEM-vpc-ENVIRONMENT/vpc/cacheSubnet3/RouteTableAssociation SYSTEMvpcENVIRONMENTvpccacheSubnet3RouteTableAssociationCCCE2449
[+] AWS::EC2::InternetGateway SYSTEM-vpc-ENVIRONMENT/vpc/IGW SYSTEMvpcENVIRONMENTvpcIGW9869729D
[+] AWS::EC2::VPCGatewayAttachment SYSTEM-vpc-ENVIRONMENT/vpc/VPCGW SYSTEMvpcENVIRONMENTvpcVPCGWECCB19DC
[+] AWS::ApiGatewayV2::VpcLink SYSTEM-vpc-ENVIRONMENT/vpc/SYSTEM-App-vpc-link-ENVIRONMENT/SYSTEM-App-vpc-link-ENVIRONMENT SYSTEMvpcENVIRONMENTvpcSYSTEMAppvpclinkENVIRONMENT55F63713
[+] AWS::EC2::SecurityGroup SYSTEM-vpc-ENVIRONMENT/vpc/SYSTEM-App-vpc-link-sg-ENVIRONMENT SYSTEMvpcENVIRONMENTvpcSYSTEMAppvpclinksgENVIRONMENT6BCED9EA
[+] AWS::EC2::SecurityGroup SYSTEM-bastion-host-SG-ENVIRONMENT SYSTEMbastionhostSGENVIRONMENT7DE50118
[+] AWS::SNS::Topic SYSTEM-operator-topic-ENVIRONMENT SYSTEMoperatortopicENVIRONMENTDDD12BF6
[+] AWS::SNS::Subscription SYSTEM-operator-topic-ENVIRONMENT/email@address.com SYSTEMoperatortopicENVIRONMENT6BB1089F
[+] AWS::SNS::Subscription SYSTEM-operator-topic-ENVIRONMENT/email@address.com SYSTEMoperatortopicENVIRONMENTF6CC5213
[+] AWS::SNS::TopicPolicy SYSTEM-operator-topic-ENVIRONMENT/Policy SYSTEMoperatortopicENVIRONMENTPolicyFB7F9EC7

What can cause CDK to shift a resource from a dependent stack into a dependency stack? This is not desired behaviour.