LinearSVC output
Your train and test data should be from same I.I.D (Independent and
Identically Distributed). I.e. each data point (both test and train)
should be independent of one another and all the data point should be
from same distribution.
There is a very high possibility that the underling datasets you are using (for train and test) are not from the same distribtu9ion.
Please, I need clarification on something.
Let's assume I have a dataset from two different website

Jaka website
Maka website

The first website has a different dataset that contains different information.
Let's assume the Jaka website has a dataset named blood dataset, hands-dataset, legs-dataset, and eyes dataset. Let's assume the Maka website also has some datasets called fingers-dataset, stomach-dataset, eyeball-dataset, toes-dataset, and kneel-datasets.
Let's assume that the largest of these datasets is fingers-dataset from the Maka website.
I used only this fingers-dataset to train LINEARSVC and saved the model.
I am then using the same model to predict the outcome of all other datasets.
The model is performing differently on all Jaka website's datasets, but giving the same result on the Maka website's datasets.  I am solving this using a regression method.
The problem here is that I am getting the same result for all the datasets on Maka's website. I am thinking maybe it is because I used one of the datasets on that website to train the model.
Please, am I missing something here?