PHP 8 warning and deprecation notice with plugin

Thank you for creating and maintaining this plugin. FYI, when I am on PHP 8.0, the following issues are logged in my debug log:

[03-Jun-2021 15:30:06 UTC] PHP Warning: Undefined array key “enable_on_checkout” in MY SITE/public/wp-content/plugins/ajax-cart-autoupdate-for-woocommerce/ajax-cart-autoupdate-for-woocommerce.php on line 332
[03-Jun-2021 15:30:07 UTC] PHP Deprecated: WC_Cart::get_checkout_url is deprecated since version 2.5! Use wc_get_checkout_url instead. in MY SITE/public/wp-includes/functions.php on line 4861

These issues throw whenever a person does business on the cart or checkout pages.
Please advise if this will be an issue on my site or if this is something that can be fixed in the plugin code on your end.

I am on WordPress 5.7.2
PHP 8.0.5
I am using version 1.5.5 of your plugin
Thank you!