It seems like this problem was present on the website for quite a while, but we didn't know about it. Yesterday, thanks to @LoopyCat letting us know and providing a lot of support, we managed to find out what caused it and resolve it pretty quickly. 🎉
The issue was present only on mobile devices, and it made the website "jump around" when performing some specific actions, and sometimes even without doing anything at all. It seems like this even caused users unwillingly giving low ratings, because the page jumped right when the rating stars were being tapped.
The root cause of the problem was in the ads, which were sometimes getting laid out incorrectly, so it could be seen when they were refreshing.
It didn't happen to everyone, but it seems like a pretty substantial fraction of our user base was affected, so I'm very glad it's fixed now. Please let me know in case you feel like the ads are causing any usability issues 🙂.
Thanks for reading, as always, and take care everyone! 🙂