Suggested

Color filtering

The problem with textures is you still can't increase their resolution by much without starting to have lock out many players on weaker phones again (and unlike PC it's literally locking out by making the game unavailable in app stores, because if the game crashes Google & Co log it and lower your internal app store rating). I still remember many got cought out last time. Without increasing texture resolution working on colours is problematic as more vibrancy, clarity and contrast in colours, and less blending effects between them washing out pixels but also boundaries you wished more clear, things become less forgiving and will highlight any deficits.

While phones like the Galaxy A55 thankfully start at 6GB and many higher end ones go past 16 GB these days even the latter just surpass what a gaming PC built on a budget had 10+ years ago, and those had 2-4 GB of dedicated GPU memory on top, while today the minimum for new PCs is more like 32 + 12 GB. That adds a lot more wriggle room for better multilayered textures on PC for devs, even though they have to keep much bigger screens and VR in mind.

That said, I do hope things, both better phone specs and game engine upgrades unlocking new tricks, work out for improved graphics not too far into the future. Even small stuff like the latest choice between glossy, matte and metallic is nice. A bit more resolution could unlock more detailed liveries and larger sponsor, game or team related stickers as well as driver details.