More ram means the processor has to work harder to run Garbage Collection. This is not the cause of your issue but I must recommend cutting that back as far as you can.
This log looks to me like a mod has a bugged advancement, sadly I can't tell which.
I can't recommend any host that advertises free hosting. It tends to mean they are all cramming everyone onto the same hardware and everyone has to share the machine's resources.
There's no crash here, just the server kicking people when they try to join before it's done starting up.
You also appear to be using Aternos, which I can't say is a reliable or quality server host.
I would recommend repairing the instance by opening its page, clicking the gear, and clicking repair. If that doesn't work, my signature has a video on how to run a Twitch modpack manually.