Welcome from ND, I'm a new flyer with a mini 3 also. Don't be intimidated, these things are fun and easy to fly. I have learned a lot here and you will too.
So, to be clear, despite your original implication, there are no FAA "regulations that limit the length of wire you can lift with a drone."
Also, that the lifting is being done "with a drone" is completely irrelevant to your non-biodegradable...
In terms of "running" of string in nature and avoiding harm, the length of the string plays a role, especially if the string is not biodegradable
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Why string length matters
Entanglement: Long strands of non-biodegradable string, such as...
Got a citation to that effect?
AI search states, "Drone regulations, specifically under FAA Part 107, don't explicitly specify a maximum length for a wire that can be lifted with a drone."