Launching a new EC2 instance 'status reason: 'Patch Group' is not a valid tag key. Launching ec2 instance failed. with Launch template.

Launching a new EC2 instance 'status reason: 'Patch Group' is not a valid tag key. Launching ec2 instance failed. with Launch template. Getting this error while using Launch template with ASG.

For the same except Launch template if I used Launch configuration then I can create ec2 instance under this ASG.

while using launch template getting an error like: The Tag key must match pattern ([0-9a-zA-Z\-_+=,@:]{1,255}}, and must not be a reserved name('.','..','_index').

According to above error if I remove space between tag key, then I can create ec2 instance.

But my main concern why it was works okay with launch configuration?