Peregrina said:
What about rope left piled outside in the garden for a few weeks? :/
No problem at all.
I used to have 10.5mm and 11mm ropes permanently rigged outside for up to 3 years before they were 'demoted' to caving use. The ones I had tested after this time were still plenty strong enough. The 11mm was at least 15kN with a Fig. 8 knot.
The much higher factors of safety and obsolescence dates applied to textile items of equipment are to account for UV degradation and the additional wear that textile items are susceptible to.
In leaving ropes out in the garden, its not the UV I would be particularly worried about, its the ants crawling all over them. That could be far more serious.
https://www.thebmc.co.uk/abseil-slings-when-ants-attack
Mark