I used to have major issues with my Sapphire Radeon RX 5700 XT and Direct X failures (not just on FFXIV, but on Guild Wars 2, WoW, etc). In end I had to return it (faulty VRAM) and replaced with a GeForce card. Not sure if the same applies to yours but I've also heard that the AMD drivers for the RX 5700 XT can be very unstable - last I heard version 19 was the most stable one available (though haven't paid attention to anything after version 22 to be honest as was rid of it by that point)