Can someone explain how copyright registration numbers work?

Thank you in advance for your help!

I just received a copyright infringement notice for bridal gloves that say “til death do us part”. I emailed the person who initiated the notice but haven’t received a reply back.

I tried looking up the Copyright number to see how I was infringing, but the Copyright number is listed as “A-146705/2023”. You can see her gloves at https://www.kerryparker.uk/products/the-tess-vow-gloves-as-seen-on-brides-com-hand-embroidered-wedding-gloves-ivory-silk-threadwork-fingerless-sheer-bridal-tulle-gloves

After researching the Copyright research page (https://cocatalog.loc.gov/cgi-bin/Pwebrecon.cgi?Search_Arg=A0000146705&Search_Code=REGS&PID=4iZ1dvQ4o1WkbJ2cdVyDcJ24q0G1&SEQ=20230810114651&CNT=25&HIST=1), the instructions are that the copyright registration number must be

“12 characters long. Type 2 letters followed by 10 digits, or 3 letters followed by 9 digits; add zeroes before the number:
VAu-598-764 is typed VAU000598764,
SR-320-918 is typed SR0000320918”

Is there something I am missing in regards to how copyright registration numbers work? I want to research the copyright so I know if I am in fact infringing.

Thank you in advance for your help.

Warmly,

Alisha