[Wed Jun 08 11:18:12.892760 2022] [proxy_fcgi:error] [pid 12190:tid 140055746156288] [client 88.8.92.178:25414] AH01071: Got error ‘PHP message: WooCommerce Extended Coupon Features error: Trying to access WC()->session while it was not yet initialized.’, referer: https://www.signaturecd.com/wp-admin/widgets.php
First of all, please update the plugin to the newest version (3.2.9). Are there more lines before/after the warning that you pasted? The url doesn’t show the error.
Can you please also send me your WC System Status Report?