That’s a separate OS setting. Signal itself has its own setting for which content is actually sent in the notification.

https://store.steampowered.com/hwsurvey

All of the results are very odd. If you look through the other categories, Simplified Chinese gained THIRTY percent, the Hard Drive categories also wildly changed, and 32 GB RAM jumped +18%. It seems to me like a bunch of Chinese systems just flooded the statistics.