This is the canonical, trailing-slash version

You reached this via a 301 from the non-slash URL. That is normal, and a crawler must handle it without looping.

Why the trailing slash matters

Most content management systems treat the trailing-slash form of a URL as canonical and 301-redirect the non-slash form to it. So /services and /services/ are not two pages; one is a permanent redirect to the other. This is correct behaviour, and every crawler has to deal with it.

Where crawlers go wrong

A crawler that quietly strips trailing slashes to deduplicate URLs turns the canonical /services/ back into /services, fetches it, gets a 301 to /services/, strips the slash again, and queues /services once more. That cycle repeats until a loop detector gives up with a 508. The fix is to preserve the trailing slash, or to follow the redirect to the canonical form and mark it visited, so the page is crawled once and never re-queued.