Tick dates randomly changing

The dates of my ticks change randomly. I record the ticks and when I come back to the website sometimes they have changed, usually to one day before but sometimes two. Happens on both mobile and the website.

So I deleted all of my ticks and I added them only from the website and not from mobile. I think the app is causing some of the problems. This seems to have stopped the issue but the dates still appear incorrect by one day on the app.