Modpack version
1.65d just updated from 1.56

Can the issue be reproduced?
Yes: Happens on every startup at "Start" in Launcher

Logs
latest.log
Guess the following line shows the issue:

Mixin config mixins.phosphor.json requires mixin subsystem version 0.7.10 but 0.7.5 was found. The mixin config will not be applied.

Then:

[java.lang.ThreadGroup:uncaughtException:1052]: at org.spongepowered.asm.mixin.transformer.MixinConfig.checkVersion(MixinConfig.java:417)

Issue
Minecraft crashes just on start in the launcher

Remember to say when you've changed the pack please :)

Deleting the memory_repo folder from your mods folder should do the trick :)

Didn't work :(
Exactly the same exception in latest.log

In addition deletion of '.mixin.out' didn't change anything. (Folder with content was recreated.)

Found it!:

I added

LagGoggles-FORGE-1.12.2-4.1.jar

to v1.56 what was working there.

LagGoggles-FAT-1.12.2-4.6.jar

is working with v1.65d / Forge #2836. Both older versions failed.

So: Solved