X-21 has bit a lot of people like that. Future doesn't like the ether in Tamiya 'acrylics', sometimes it clears up on it's own.

Doesn't Testors have matte clear under the Model Acrylic brand?

I use Vallejo only at this point, between their Panzer Ace range and their new tinted Poly primers, they have all I need. They have 3 types of acrylic clear.

One thing I used to do years ago with static models was 'dust' them with Tamiya buff. That knocked the shine off the Future and dulled the color, adding a realist dirt appearance. Dry pigments do the same. I'd experiment a bit if you wanted to try that route. Dusting with an AB can get away from you quickly.