I've been considering using Backblaze for both personal and company needs -- and we're talking 50+ TB here -- but this incident made me reconsider.

I'd still use Backblaze but that's VERY dependent on how do you handle this. Just saying "we fixed it" doesn't answer the much more fundamental question of "what is the FB tracking pixel doing in a privacy-critical page in the first place?".

Please, do a thorough post-mortem analysis and publish it. Looking at the comments here, this could mean you get or lose the business of many.