As of today, Date Validation Failing | Older 3x install

<%- if @topic_view.topic.tags.present? %>
<%= t 'js.tagging.tags' %>: <%- @topic_view.topic.tags.each do |t| %> <%= t %> <%- end %>
<% end %>

Silverstripe Version:
Not entirely sure to be honest… but it’s in the 3’s and quite customized.

Question:

While I know this is very difficult to begin understanding, it’s more difficult explaining, as there have been multiple developers over the years on this site. But, I will say I have 3 different ‘versions’ (sites) 1 of which is on a different server entirely – and all three stopped ‘working’ today. They all worked fine yesterday, but now… not so much.

I have verified there have been no MySQL updates, no PHP updates, no PHP Environment updates, and looked at all file dates over the past 36 hours to see what’s new – and … there’s nothing. I’m totally stumped at what is going on but here’s what happens:

It’s a customized form, that upon submission has various required fields looked at, and until today, all is fine. But now, all 3 date fields (start date, end date, submission date [read-only]) come back as if they were not submitted, and even removes the read-only date.

I can’t find anything in Apache’s logs that suggest foul play, I can’t find anything in mod_sec, I can’t find anything in Chrome or Safari’s console… And I can’t find anything in the SS logs that suggest there is a related problem.

Has anyone been cursed with the Cinco De Mayo date field validation hex?

Thanks in advance to you all. :).