clearstream
(He, Him)
In principle, 5th edition DCs are objective, not subjective. Meaning that what you may call difficult to one character should rightly be easy to another.It really helps to quote people when you ask them something. I'll assume you're asking me as I just posted and said 25% and hard in my response.
You have it backwards. Something being a hard/difficult task means the character has a 25% chance to do it. What's hard/difficult depends on the character. What's hard for the GOAT is impossible for the average schmoe. What's hard for the average schmoe is laughably easy for the GOAT. It's not a fixed scale of "this is a hard task" but "this is an easy task." It's relative.
If you want to turn it into a fixed scale, determine what would be a 25% for each of those characters. Keeping things flexible and relative is a much simpler way to run things and there's a lot less math and spreadsheets involved.
That said, there is nothing inherently difficult about rolling dice, we're only discussing which next world we are likely to be in. To me, a difficult task therefore is one with severe possible consequences.
Accepting the chance of those severe consequences elevates the character. Making them heroic. One does not need the consequences to be overwhelmingly likely: the calculation is % * $ where dollar stands for cost or consequence.