One of the things that you learn when being taught to type on a typewriter is to leave two spaces between sentences. Two-spaced gaps between sentences is a recognizable sign that a page is typewritten, but the rule wasn’t designed with that typographic end in mind. It was meant to discourage having to interrupt the first word of a sentence with a hyphen and a line break. By typing an extra space, the typist was more likely to get the warning bell indicating that the end of the line was approaching. The typist would know to hit return and start fresh on the next line rather than risk running out of space on the first word of a sentence.
I learned how to touch type on an IBM Selectric Typewriter in Mr. Fredricks’ keyboarding class during my freshman year of high school. Mine was the last typing class in the school that used typewriters. The next year’s classes used PCs running WordPerfect on DOS. With auto-wrap they presumably weren’t taught that rule. It was outdated.
I still type two spaces at the end of sentences. It’s habit. But your browser takes back the second one and keeps it for itself.