A subnet is ALWAYS going to be associated with a route table.
If you don't explicitly it, it will use whatever RT is set as the Main (=Yes) for the respective VPC..but if you don't explicitly set it via subnets.route tables..edit subnet association, and choose the RT, that's what you see.
New VPC Subnets and Transit Gateway attachmentAccepted AnswerEXPERTasked 3 years ago
API GW Websockets and public subnetsAccepted Answerasked 7 months ago
VPC Peering not working as expectedasked 9 months ago
Route Public IPv4 Address within VPCAccepted Answerasked 2 years ago
Private Instance and Public ELB HTTPS Problem.asked 9 days ago
TGW Route Table entriesAccepted Answerasked 2 years ago
VPC - Public/Private Subnets - Unable to access from internetasked 3 years ago
Subnets associated with a route table show as not associated with any RTasked 4 years ago
CoreDNS can't resolve on public subnet in VPC with public and private subneasked 4 years ago
cloud-init not setting default route to NAT Gatewayasked 2 years ago