Can somebody tells me what time zone does duolingo website/servers works on? Because I sometimes miss day streaks just because my country time zone is not synched with duolingo apparently so it thinks I haven't practiced but I did. Or maybe I'm wrong and it checks 24-hours intervals? Then I don't think it's the best idea because there are some days I practice in the morning and the day after I practice in the evening so it's more than 24 hours but it is considered day by day. Not that it is so important to me but just trying to grasp the concept and the logic behind it.
It is based off the country you are located in when you first created your DL account.
(I think, but haven't been able to confirm that) You can find out which timezone DL has you located in by right clicking on the web page, clicking view page source, and searching (using ctrl F) for "timezone".
I've seen people like Xneb say that they have changed their timezone, but DL staff has said over and over again that it cannot be changed, so there is a disconnect in information.
I do know that simply changing you computer's time will not change your 'duolingo day'. What can be confusing though is that your line graph that shows how many points your earn each day is based off your local computer's time, which can make it appear that you earned points for the day, but you streak will not be continued.
Normally it's midnight for the country you're in, and the time to continue your streak goes from midnight to midnight. Your time-zone can be changed for the country you're in by changing the time on your computer and then restarting your browser after you've changed your time zone (I don't know if it works for everyone, because other people don't seem to be able to do it, and I don't know if it works for the phone apps). But the website should use the local time you have set up. It should be that if you do it at, for example, 8am today, you should have until 11:59pm tomorrow to continue the streak. If it's not working like this then contact duolingo using the support button on the left hand side of the screen
After going to Denmark, coming back to England, my streak reset at 11pm until I restarted my browser (I keep my browser open most of the time on my laptop, so it was like this for about a week and didn't change the clock on my laptop until after I opened it because I forgot). I don't know how it works or anything, just speaking from what happened and what worked to change it for me