What's hitting my daily io limit?

Hi and welcome to the forum

The IO limit is based on how much storage bandwidth your account uses. If you read and write many (large) files from your account, this generates high IO usage. Normally, IO usage is throttled to prevent a few big accounts from hogging all the storage read/write capacity, but accounts that consistently overuse the storage are suspended for 24 hours.

Amount of MB per second the scripts of your account are reading and writing from the underlying storage. If you have scripts that continuously read or write many files, or big files, on your account, that would lead to high IO usage

It could be Malware, all the way to some plugin, cron, etc.

Unfortunately, we cannot give you the exact cause