An important step here that is missing here is evaluating if your fix is going to cause other, potentially worse problems. I suspect that in this case, it's fairly unlikely that increasing the maximum POST body size to 60 MB is going to cause problems - eyeballing that Sendgrid chart, it looks like we are not dealing with very high throughput here. But it's not hard to imagine a situation where tripling the max POST body size would result in a large increase in server memory usage, which could result in things like OOM kills, which could result in a lot of people not getting their reply emails or whatever.

So don't just rush a fix out. Think about what the effects of a configuration change like this might be, and whether you are just making more problems for yourself down the line trying to fix something quickly.