(1)Minecraft 1.8 To 1.19

Servers that let clients from multiple Minecraft versions join, usually via ViaVersion-style plugins, covering everything from 1.8 up through 1.19. They’re typically running a newer server jar but keep 1.8-compatible combat and packet support, so you get mixed-era PvP and cross-version access with some newer features limited or behaving differently for older clients.