Language Change Issue

I have noticed something weird happen whenever I change the language of the site in settings. My laptop language is set to French. The site language was originally in English and has always been in English for me and it didn't change when I set my laptop language to French.

So, a couple of weeks ago I changed the site language to French. That worked flawlessly. But a couple of hours later, I tried changing it back to English and that seemingly worked because the Settings page had turned into English. But, when I left the Settings page, the entire site had changed back to French. Then I went back to Settings and changed it back to English but the same thing happened again. When I left the Settings page, it had gone back to being French. I then went back to the Settings page and the Settings page was also back to French.

Then I changed the site language to Spanish and the site language stayed as Spanish regardless of where in the site I went to. It didn't automatically change back to French. I then changed the site language from Spanish to Korean and the site language also stayed as Korean regardless of where I was on the site. It did not automatically change to French.

Then I went back and changed the language to English. Now, note at this point that the site language is still in Korean and I'm trying to change it from Korean to English. It worked only while I was in the Settings page. Once I left the settings page, the site language had changed back to French like the earlier time.

Then I changed my laptop language to English and when I went to change the site language from French to English, it worked. The site language stayed as English regardless of where in the site I went to.

I might say it was my computer language but it doesn't make sense. If it's my computer, then regardless of what language I change to, it should always come back to French. But it let me change to Spanish and Korean without changing it back to French. Why is it only when I wanted to change it back to English that is automatically changed back to French?

What I don't understand is this: Why would you put a Language Change option when the site decides to work with your device language instead? Is that deliberate or is it a bug? Besides, the point of a Language Change option on a site is to change the site language to any language regardless of what the device language is.

For clarification, at the beginning of this issue, my laptop language was in French. I had to change it to English to fix it. I prefer my laptop language to be set to French but I don't want it to have any effect on the site language especially since there's a language change button on the site.

So, I don't know, is this a bug or not? It seems like a bug.