base64 does not have the problem here, iMessage has. Frustrating.

Agreed, iMessage should have URL detection that supersedes any other string parsing.

The fault doesn't lie in iMessage, it lies in Apple in general. Google's AOSP keyboard will IMMEDIATELY detect that you are writing a link when you'll put http(s):// in front of whatever else you're currently writing and will just shut up and let you finish without interrupting every 2 seconds with autocorrection suggestions. This does not happen on Apple's i(Pad/O)S keyboard, where typing a link will usually leave the user with an excercise in frustration, trying to fight over the autocorrection, which, for the 17th time, has decided to convert your URL into "normal words". Not even changing the keyboard seems to fix it, as, from what I remember, Gboard still uses Apple's prediction engine...

Curious if English is your mother tongue, and if so, which locale?

As a native speaker of en-US, I would write this as "base64 does not have the problem here, iMessage does."

Right before I was forked my parent did “export LC_ALL=C” and here I am.

Originally en-AU. I was trying to match the "have" with a "has". My sentence has a truncated " the problem" in my head.

Your version reads more correct, thanks for pointing it out.

Surely that's something that Apple should fix, rather than everyone else working around it?

This isn't at all comparable. It's purely an Apple problem.