At this time, Bubble's API connector does not allow disabling SSL and defaults to checking certificates for security purposes. Additionally, it's not advisable to send data over unencrypted connections since the data can be vulnerable to unauthorized access and subject to "man in the middle" style attacks.

For more context, Bubble uses SSL for all calls, and your server's certificate is coming back as self-signed, which is not trustworthy by default. You'll want to set up your server's API to sign certificates over SSL.