DaemonUmbra

If the launcher doesn't even start properly have you tried going to Mojang for support?

Do you have any other versions of Java installed? If so, try uninstalling them all so shared files get deleted, then reinstall.

Is this a pre-made modpack or one you made?

Provide a log from a supported version (currently 1.16.5 and 1.15.2)

...and have patience, I'm not here 24/7. Though, you won't get help now because your log indicates you're a pirate... User was banned for piracy Buy the game

Why even use 1.16.1 instead of 1.16.5?

Because if it was pre-made I would have had you report this to the pack dev. Remove Randompatches.

Forge uses more threads and uses more of your CPU's power, when running your tests were you viewing CPU usage as a single value or was it broken down by core or thread?

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

1.12.2 is not supported anymore due to its age, but here's something for you to google: "minecraft launcher installation game directory"

It's not the crash report, it's a log file in .minecraft/logs (more info in my signature below, just expand the spoiler)

Please provide debug.log (more info on where it is and how to provide it in my signature below, just expand the spoiler)

Please provide debug.log (more info on where it is and how to provide it in my signature below, just expand the spoiler)

Is this a pre-made modpack or something you made?

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Please provide the full path to where you are looking for logs

1.8 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Forge's Installers can be found on the Files Page. Most mods need to be installed on both the server and the client. Forge and other mods cannot generally be used on versions they were not designed for, however the differences between 1.16.4 and 1.16.5 were so slight that 1.16.4 mods will generally work on 1.16.5

Do you have Java installed?

1.8 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Most mods need to be installed on the client AND the server. I hope by "forge site" you mean CurseForge (Note: no affiliation between us and them) 1.16.4 mods should "just work" on 1.16.5 unless they did something the wrong way that now won't work

Did you make any alterations to the pack?

They'll be that way, but Forge is set to allow 1.16.4 mods on 1.16.5 because the change was so small

Why use 1.16.4 when 1.16.5 is literally the same but with a couple bugfixes? Plus, at some point during 1.16.5 the issue you're experiencing was fixed.

1.10 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.