Use any class for markdown-it-container instead of just a single one.

markdown-it-container-dynamic.js

const markdownItContainer = require('markdown-it-container');
const markdownIt = require('markdown-it');

const md = new markdownIt().use(markdownItContainer, 'dynamic', {
	validate: function () {
		return true;
	},
	render: function (tokens, idx) {
		const token = tokens[idx];
		return token.nesting === 1
			? '<div class="' + token.info.trim() + '">'
			: '</div>';
	},
});

console.log(
	md.render(`
::: my-dynamic-block
Hello, world!
:::`),
);

Got it. Thanks!