Uncertainty for step ratios

The uncertainty band for step ratio plots looks too small:

• step https://uhepp.org/p/d96f7b6f-d2ce-4d73-8a51-846dec8474fe
• points https://uhepp.org/p/0590f218-f54a-4d19-9687-3092d1e17cd2

Probably similar to 8cf6e84b