I believe you can do that with texture pack, meaning that to you all elytras will look like parrot wings, but other players won't see it like that. I don't know what the file is called for the elytra texture, but you can look for texture packs that modify elytras, decompress the zip and see how they do it.
"100% Safe, Open-Source & Virus-Free." well if it says so it must be safe. I suggest you post links to the mods as an alternative, because it isn't open-source if you don't publish/link to the source and there is no proof that there wasn't any tampering on the way(that website you used to upload looks really dodgy).
also I tried to download it just to check it and the website says "Ad Block or VPN Block Detected" which means that:
that ain't no direct download!
that website blocks ad blockers(they want money) and VPNs(they don't like people being anonymous).
that they suck at double checking what they wrote because I doubt they intended to write "VPN Block"!
and, last of all, I'm pretty sure this is written by a LLM:
one list uses a unicode bullet points but another list uses dashes?
those icons at the beginning of each title just scream LLM!
that's a bit too much: +200% fps boost, 100% safe and the weird sentence at the start that just feels off.
EDIT: I reloaded the page and saw that image, that's horrible dude!
I didn't try it but it's all the common performance mods, so it should be pretty good, although definitely not +200%! also I doubt it's really worth making a modpack out of it, although those mods are probably a must for any instance(except if you use vulkanmod).
I'm pretty sure a datapack can't do anything about that, sadly. but yeah, it's weird it's not considered a bug; anyone who played minecraft for some time probably knows about it but no one ever tried to fix this or file a bug report...
I guess it would be possible to look where that's coming from, then it might be possible to fix it with a mod or a shader. I did not find any mods doing that, so ig no one ever tried. good luck...
well, it gives an unfair advantage against other plays who are not using xray. on servers where xray is allowed, it's not cheating and not unfair because everyone is doing it.
actually I recently(in the last few weeks) discovered how comparators work, now I'm pretty good at using them! I can finally do 1337 redstone! it's amazing how simple but somehow really weird and hard to understand comparators are.
noooooo I told you to not make any mistakes and you asked arandomcat, which, looking at their answer, may(or may not) have been a mistake. BAD AI
also why did you ask them? genuinely curious, are they the only one to know the answer to the question of life, the universe, and redstone comparators?