Vertical text doesn't fall back to rotated versions of horizontal glyphs when necessary
I last observed this in January so it might be outdated, but if this is fixed now I would be very happy to know! I was just told to report this upstream by a dependent project and found my way here.
Unicode specifies what glyphs have to fall back to rotated versions of their horizontal glyphs if the font doesn't provide a direct fallback: http://www.unicode.org/Public/vertical/revision-17/VerticalOrientation-17.txt
Basically, this issue manifests when CJK fonts don't provide vertical presentation forms for punctuation characters that have to be rotated to display correctly in vertical text.
(ignore the contents of the Japanese text, it's just what I had on hand at the time I took the screenshot.)
Top is a piece of software that uses pango (tesseract 4's text2image), bottom is Firefox (which uses harfbuzz etc. directly). The same exact font file was used. Notice the