Why does my slug come out looking like gibberish?

Hi there,

I’ve found a page on my site that has a slug filled with gibberish. Lots of “%” and numbers. But on the page edit view, the slug is the one I gave it (similar to the title).

I don’t know what this problem is. I have scans running on my site for malware with nothing detected, and the page otherwise loads well and shows up in search (albeit several pages low).

How do I fix this? But more importantly, what is the cause of it?

Thanks

The page I need help with: [log in to see the link]