tangentially related: 15 or maybe 20 years ago i worked at a repair shop and someone brought in a TV that they said switched to spanish every night at 5pm.
they were watching over the air channels and there was only a setting in the tv for menu language. sure enough though, at 5pm that night we watched as the tv started speaking in spanish. we tried a few more channels and found that all but one or two were in spanish.
as it turns out, some stations broadcast audio in multiple languages and some tvs allow you to change the preference. sadly for this person, the used tv they bought came from a spanish speaking country and didn't have anyway to change that preference.
My Bluetooth speaker switched to Chinese after a few years of use. I have no idea of how it did it and no idea of how to revert it. There is no reference to it in the manuals.
A few days before, I brought a robot vacuum home. It was made and purchased in China. When I started it for the first time, it bumped into my server and unplugged it.
Therefore a state-sponsored cyberattack is not out of the question.
I have a pair of Bluetooth headphones that indexes through 3 languages (Mandarin, Korean, English) on startup when you also hold down some other button besides power (play/pause IIRC). I don't think it's documented. Maybe your speaker is similar.
they were watching over the air channels and there was only a setting in the tv for menu language. sure enough though, at 5pm that night we watched as the tv started speaking in spanish. we tried a few more channels and found that all but one or two were in spanish.
as it turns out, some stations broadcast audio in multiple languages and some tvs allow you to change the preference. sadly for this person, the used tv they bought came from a spanish speaking country and didn't have anyway to change that preference.