I use Fiddler frequently and always update when recommended. I am assuming the old version preceded this release by one revision. Since it is gone, I have no way of checking.
v5.0.20181.13826 for .NET 4.6.1
Built: Monday, March 12, 2018
I have used Fiddler yesterday and earlier today without issue. The fonts only changed after the update.
Not sure how Windows could cause this, but there may be some hidden dependency.
On the net, most comments stated the issue was particularly bad on higher resolution displays, which we use.
Anyway, I hope to find a fix because I have to get within about 8 to 10 inches to read the text fields.
I'll start looking into Windows as the source.
Thanks for taking the time to look at this issue.