To be accurate this is only a warning, but php 8 will display it on the frontend by default, even with wp_debug set to “false”.
Default error reporting is set to E_ALL in php 8. https://php.watch/versions/8.0/error-display-E_ALL
Thanks for your reply, John.
For anyone that still needs to track subscription renewals, I was able to get this going (separate from this plugin) by hooking into woocommerce_subscription_renewal_payment_complete and posting to Google Analytics via Measurement Protocol.
