Product add-ons are subtracted as a discount on order status change

Hello, I noticed a strange error. I use a plugin to offer product add ons. (It doesn’t matter which one, I tried multiple plugins but the error is being reproduced as long as Premmerce is active.)

Everything is fine until the user completes the order and the order remains in the same status. As soon as the status is changed though, the add-ons that should be added to the price (and are correctly added in the original status) are instantly subtracted as a “coupon” discount. From here on it is not possible to change the order back to the original total and the order remains with the wrong price.

I have deactivated all of my plugins and this is the only one that seems to be interfering.

Any help would be appreciated.