The most common usagr is pairing "someone" with "they"; this can be easily avoided by using "people" in place of "someone."
Anyone who speaks German or Russian just for example has to plane before speaking; there are cases, gendered nouns, complex conjugation. Most Americans never do that. Every instance of the singular they represents someone who has painted itself into a grammatical corner.
It bothers me immensely. Reading it feels like walking into a telephone pole.
I know in a world with so many desperately urgent issues this seems like small thing to get fussed out about but it annoys the daylights out of me.