RGB colors are not supported in Anvil update
When i have a Display Name of an enchant with RGB colors (i've tried only with gradient, honestly i haven't tested yet with simple <#colors> but i've used gradient:#color1:#color2 and but it isn't the end of the gradient the problem) it happens that RGB enchant1 + RGB enchant2 = NOT RGB enchant3.
i upload two simple screenshoots to explain easily the problem.
In first screen i have RGB Burning I enchants (in both slots) and they correctly give Burning II but the color has to be the same RGB not the basic color