Disabling blocks from the block inserter

function get_plugin_settings() {
	$disabled_blocks = [];
    $disabled_blocks[] = 'my/blockname';

	return [
		'disabledBlocks' => $disabled_blocks,
	];
}

# enqueue scripts hook:
	wp_localize_script(
		'myblocks-editor',
		'myBlocksSettings',
		get_plugin_settings()
	);

Javascript:

import { addFilter } from '@wordpress/hooks';

// Define disabled blocks.
// If you need to rely on logic available only in PHP,
// pass this data using a global variable instead.
const DISABLED_BLOCKS = window.myBlocksSettings.disabledBlocks;

/**
 * Conditionally enable/disable insertion of blocks.
 *
 * Ensure sure this function runs BEFORE you register your blocks.
 *
 * @param {object} settings block type definition
 * @param {string} name name of the block type
 * @returns {object} block type settings
 */
function filterBlockRegistration( settings, name ) {
	if ( ! DISABLED_BLOCKS.includes( name ) ) {
		return settings;
	}

	// Ensure there is a supports section
	if ( undefined === settings.supports ) {
		settings.supports = {};
	}

	// Disable the UI to add this block .
	// If the block is added in another way,
	// e.g. legacy, programmatically, copy-paste, it will still work.
	settings.supports.inserter = false;

	return settings;
}

addFilter(
	'blocks.registerBlockType',
	'myNamespace',
	filterBlockRegistration
);