Custom Field Validation Issue

-- HikaShop version -- : 6.4.0
-- Joomla version -- : 5.4.3
-- PHP version -- : 8.2.30
-- Browser(s) name and version -- : Firefox 148.0.2

I just updated our site to Business 6.4.0 from 6.1.0. I have a custom field that is required, but no regex was specified. With 6.1.0, the customer could put any text in the box and it would be accepted. With 6.4.0, no matter what the customer puts in the box, it shows the custom error message. I did try several regular expressions and all still resulted in the custom error message. I've had to make it non-required for now.

Can I just reinstall 6.1.0 over 6.4.0?

I also found that variants are not working properly. There's two choices, one that add $5 and the other that doesn't. When selecting the option with no added cost and then adding the product to the shopping cart, what shows up in the cart is with the $5 extra option.

Also, I can't say that I like the backend changes.