Chartjs-Why is my subtitle not appearing in chart?

This is because you are using treeshaking and not importing and registering the subtitle plugin. Adding the import and register like so will resolve the issue:

import {Chart, SubTitle} from 'chart.js';

Chart.register(SubTitle);

Or you can just let chart.js handle it and import and register everything like so:

import Chart from 'chart.js/auto';