Vertical lines are not contiguous with most fonts

For example, compare this segmented vertical line with Pragmata Pro:

to this contiguous line with Fira Code:

Of the fonts I have tried, which include all the ones included by default, a few of the ones in the blinksh/fonts repository, and Iosevka, only Fira Code and Source Code Pro work perfectly. I think Menlo and some other font work also work well but only at precise font sizes, often too large for my needs.

Pragmata Pro, my favourite, showcases their beautiful line drawing characters on [its website.](
https://www.fsd.it/shop/fonts/pragmatapro) I know some of the other fonts can draw contiguous lines too.

Reproduce the segmented vertical-line rendering on iOS using Pragmata Pro and the other fonts described, then compare it with Fira Code and Source Code Pro. Trace the terminal rendering entry point responsible for line-drawing characters; done means vertical lines remain contiguous across the reported fonts and font sizes.

Written by the indexing model from the issue text.