The strip is a range test, and the range is not WinAnsi's. `[^\x20-\xFF]` removes every code point above U+00FF [8]. The character that started this, Ł, is U+0141, so it goes [7]. The euro sign at U+20AC and the curly quotes at U+2018 and above also go, and WinAnsi encodes all of those without complaint [6][1]. So one regex deletes two disjoint sets: characters the standard font genuinely cannot draw, and characters it can. It is doing more work than it was asked to do.
Nothing downstream sees either deletion. The file is a valid PDF, no exception is raised, and the logs stay clean [9]. A generator suite asserts on the input string and on the absence of a throw, and neither of those changes when a letter vanishes between `drawText` and the page. pdf-lib's own error was the useful artifact here, naming both the character and its hex code point [7]. Trading it for a green test run swaps a stack trace for a document defect. The author of the write-up is blunt about the only check that catches it: render a page with non-Latin-1 text in it and look at it with your eyes [9].
The figures most likely to be copied out of this are the font sizes, so it is worth saying what they rest on. One unsubsetted Archivo weight is about 180 KB, which is why three weights add roughly half a megabyte to every document generated [12][2]. With `subset: true`, the same three weights inside the author's four-page invoice land at 35 KB, because only the glyphs actually drawn get embedded [13]. Call it fifteen times smaller [2]. That ratio transfers to documents that draw a comparable glyph set and no further. Subset size follows distinct glyphs used, so a customer base heavy on diacritics will not compress like one Polish name in an English template, and caching the font files in a module-level variable shortens the read on warm invocations rather than the subset [14].
With a rasteriser already pointed at the output, two layout defects turned up that reading the code would not have surfaced [18]. The totals block right-aligned its figure at 20pt Black in a column sized for four digits: $2,160.00 fit, and 86,832.81 PLN ran back over the words TOTAL DUE [19]. That is the same failure class as the missing letter, and the same instrument catches both, which is the argument for keeping a rendered-page check inside the pipeline instead of waiting for it to arrive as a bug report.
