How to detect the HLines correctly?

Dear all,
I like to know how to detect the hLines correctly.

• Which module does it?
• How to improve it?

See the picture: No HLine deteced.

The Fille might be seen as kind of but why is it so difficult to see the lines?
Thank You all for Your contributions!

Testfile to receive from: https://www.cftc.gov/media/10156/AI_RFC_012524/download
Result header of first page:
{"Transcoder":"pdf2json@3.0.5 [https://github.com/modesty/pdf2json]",
"Meta":{"PDFFormatVersion":"1.6", "IsAcroFormPresent":false,"IsXFAPresent":false,"
Title":"Request for Comment on the Use of Artificial Intelligence in CFTC-Regulated Markets",
"Author":"CFTC","Subject":"Request for Comment on the Use of Artificial Intelligence in CFTC-Regulated Markets",
"Keywords":"","Creator":"Acrobat PDFMaker 23 for Word", "Producer":"Adobe PDF Library 23.6.156", "CreationDate":"D:20240125143132-05'00'","ModDate":"D:20240125172143-05'00'"}},
"Pages":[{"Width":38.25,"Height":49.5**,"HLines":[],"VLines":[],**
"Fills":[{"x":4.5,"y":36.57,"w":9,"h":0.045,"oc":"#000"},
{"x":7.755,"y":40.5,"w":19.957,"h":0.03,"oc":"#006fc0"}],

Start by reproducing the result with the linked CFTC PDF and inspect the generated Pages.HLines, VLines, and Fills fields. The issue names no source file, test, or module; done should establish which module handles line detection and whether the reported horizontal lines are represented correctly.