Issue with CloudFlare response

Hi guys, I have a page where I can filter a list of results.
the website is hosted on IIS.

my query parameters are like so:
?contractOption=All&occurrenceRule=&occurrenceType=&selectedName=&startDate=10%2f03%2f2025&startDateMax=14%2f03%2f2025


the issue is, if I search for any dates where startDateMax is less than the 14th of March, the response is correct.
if I search anything from the date of 14th march or later on, without the other parameters changed,
I get the error
Cloudflare encountered an error processing this request: Bad Gateway

with status 502.

so the URL for the correct response would be this:
?contractOption=All&occurrenceRule=&occurrenceType=&selectedName=&startDate=10%2f03%2f2025&startDateMax=13%2f03%2f2025


I believe this is an issue with CloudFlare because:
I connecting with Remote Desktop to the server, accessed the same URLs from the website's local IP (bypassing CloudFlare)
and the pages load correctly.

I also see no errors in my IIS logs or Event Viewer.
and if i check in CF > Analytics & Logs > HTTP Traffic and I find those calls, the Edge status codes are all
200 OK
, same thing with the Origin Status code.

any ideas? and thank you in advance
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