TOPIC: PHP 8 Trouble

I have migrated my site to PHP 8 and the Ebook Store plugin, which I purchased from you in December 2020, is causing an issue: if a customer purchases more than one e-book, it only sends the first one and doesn't send the others, which doesn't happen in PHP 7.5. Do you have any solution for this?

I am having issues with php 8.x too. Switching to 7.x resolves it. Trying to add an ebook, and this error occurs:
Error message: Uncaught TypeError: Cannot access offset of type string on string in /home/xxxxxxxxxx/web/xxxxxxxx.com/public_html/wp-content/plugins/ebook-store/functions.php:267

Switch to php 7.4, and no more error.