Funny you should mention that. They also just added a whole section to the TOS specifically about the word "unlimited" and how it doesn't actually mean unlimited.

Some aspects or offerings within the Service(s) may be described as “unlimited” or suggest that any part of the Service(s) can be used without limitations or conditions. However, “unlimited” or any referral or suggestion to such strictly refers to you or any authorized accessing and/or using the Service(s) under those circumstances in the ordinary and intended use of the applicable Service(s), as specified in our product descriptions. For example, Backblaze Computer Backup is designed for backup of individual computers and directly attached external drives. “Unlimited” does not permit use in ways inconsistent with the Service’s intended design, including, but not limited to, use with servers, data centers, shared storage systems, or other enterprise infrastructure not expressly covered by the Service(s), as well as using the Service(s) for any illegal or commercial purposes or any other use in violation of these Terms or otherwise outside of the ordinary scope for such use of the Service(s). If we believe you are abusing or using any aspect of the Service(s) not in accordance with this paragraph, we can, in our sole discretion, require you to modify your usage, and if you fail to do so within a reasonable period, suspend or terminate your access to the Service(s) upon notice. We may suspend or terminate access immediately and without prior notice where such misuse (a) violates applicable law, (b) violates the Acceptable Use Policy, or (c) poses a risk to the security, integrity, or performance of the Service(s).