When I used to service satellite systems back in the day, a common fault was spiders nests in the feed horn for the LNB, often caused by a missing cover, or even just a tiny crack in the cover.
To be fair I mostly came across such a situation with older systems that used mechanical or magnetic feed systems with separate LNB and feed horn.
It’s would be a rare find on a Sky system with a well sealed universal LNB, but I have known it happen.
If its Spiders nests after you clean it out of the feed horn give it a squirt with SpidEx - keeps spiders away for years. Worked fine on my CCTV
cameras - available from CPC but also other suppliers no doubt. Costs about a tenner.