I’ve been doing some research about doing mine. Haven’t found any verifiable warranty denials, but have found several recommendations not to go any darker than 70% to keep from reflecting too much heat back into the glass. Apparently that is what causes any issues. I’ve decided to go with Llumar Air 80. It’s a classed as a clear film (slight bluish tint on clear glass, but supposedly unnoticeable on factory tinted glass). It is supposed to block approximately 46% of the heat. Blocks 60% of IR light and 99% of UV light. I found it recommended by several tint shops online, and it’s the only film my local shop recommends for sunroofs. Just my 2cents.
https://llumar.com/na/en/automotive/window-tint/clear/