Shipping tax not calculated correctly

Unfortunately, I have a problem with the shipping tax and hope to get some help.

In the woocommerce tax options, I have set the shipping to the standard tax rate. Our standard tax rate is 20%. However, the tax on shipping is calculated according to the tax rates of the products in the order. For example, if 50% of the total is taxed 20% and 50% the reduced rate of 10%, then the shipping is also split 50/50 with one half taxed at 20% and the other 10%. If there are only items with 10% tax in the cart, then the shipping is also calculated at 10%.

I have unchecked ‘shipping’ in the Reduced Rate class, but it makes no difference. If I uncheck it everywhere, in standard and reduced, shipping isn’t taxed, but if I check one or the other, it is checked according to what’s in the cart and not according to the checked tax rate.

I have added a third tax class just for shipping and made it 20%, but it’s the same as with the others.

Now ideally I would love if the tax rate of shipping was always the highest tax class in the order, but as far as I know, that’s not possible in woocommerce, so I would be happy if I could simply get a consistent tax rate of 20% to work. Thanks for your help!