During creating a new connection from the API connector where I updated Base URL field before, there is prefilled the old value in the Base URL field. When I look back to the API connector, there is the updated value.

This happens for Base URL and Host fields as same as for the address field for SOAP.
The workaround is to change pre-filled values during creating a new connection but in this case, the editing Base URL and Host values on the API Connector is ineffective.