It goes into an endless loop

After the pop-up screen offering the free gift, if we chose the free gift instead of ‘No thanks’, multiple messages appear on the bottom left of the screen, including: ‘Connecting..”transferring’, and then the pop-up window appears again to offer the free gift but no free gift is added to the cart. This loop continues until ‘no thanks’ is selected.

https://wordpress.org/plugins/woocommerce-multiple-free-gift/