Try to re-create webhooks.
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Go to Stripe Payments -> Settings, Subscriptions tab. Click Delete Webhooks button, also click Clear Cache button. Then create webhooks for both live and test modes. Then send another test webhook from Stripe Dashboard. Make sure to select customer.subscription.updated webhook type. Then check logs.
If nothing in logs, we need to log in and check your site. Would be nice if you have a staging website.