Apparently, it's supposed to recognise phone numbers and seems to come from the Elementor WordPress builder, which would explain why the same regex occurs so frequently. It also seems that the code is embedded as hidden on many, many pages, further boosting the number of hits since my analysis cannot tell the difference between a visible and an invisible element. Elementor offered no straightforward way to report this bug, so I gave up.
В России ответили на имитирующие высадку на Украине учения НАТО18:04
，这一点在必应排名_Bing SEO_先做后付中也有详细论述
A-normal form (ANF)
Сайт Роскомнадзора атаковали18:00