Hello! I'm a huge fan of the Lunar Mod "1.7 Visuals" that brings 1.7 animations to the 1.8 minecraft version.
As of now, it's a mod that's only available for 1.8 but it would be great to make it available for other minecraft versions.
The suggestion is not to bring 1.8/1.7 combat system to newer versions as it may cause problems with servers. This suggestion is more about making Lunar compatible with the OldCombatMechanics plugin.
OldCombatMechanics is a spigot plugin that aims to simulate 1.8 PvP to newer versions of Minecraft. The suggestion I'm talking about is to detect when OldCombatMechanics is turned on and enable the Lunar Mod "1.7 Visuals" only when OldCombatMechanics is on.
The question is "how to detect when OldCombatMechanics is enabled". According to OldCombatMechanics' config file (you can see in the screenshot) the plugin sets the speed/haste of the item at 40, which is the minimum value to match 1.7 and 1.8 pvp style.
Lunar could bring 1.7 Visuals Mod to newer versions of minecraft but only turn on when the weapon the player has in hands has a speed/haste of 40. This way, there would be no problem when the mod is turned on, but the plugin is not used. It would only happen when the speed is set to 40, which is not possible in vanilla and can be achieved only via command blocks or plugins.
I think that it may be a good first step for PvP servers to upgrade to newer versions of the game. My personal opinion is that Mojang should give the players the choice to play with old PvP style or not with a gamerule, since minecraft is a sandbox game it would make sense. But it's pretty obvious Mojang does not want to follow that route. Most servers are running in 1.20 nowadays, but there's still a need for 1.8 style since OldCombatMechanic has been downloaded over 176k times on spigot's website. I think that it won't hurt nor disturb anyone while giving more comfort to players and maybe push forward the community.