GDPR, General Data Protection Regulation... While many have heard this term, not everyone knows what it means. I'll come out of the gate saying I'm not an expert, nor a lawyer. In a very general sense, it's about online privacy and giving individual users more control over their information what is shared with whom.
To that end, Steam has rolled out a change of their own with regards to profile privacy. Whether this is related to GDPR or not, no one will know, but the timing is quite coincidental.
How this impacts the Steam Profile Integration application... By default, Steam is setting everyone's privacy settings pretty secure. Meaning less data will be pulled for you users.
You'll start seeing Profiles with:
0 hours played in the last 2 weeks quite a bit more frequently
No statistics for recently played games (games played in the last 2 weeks)
No statistics for owned games
No, or limited, statistics for total playtime for games.
This doesn't mean the Steam Profile Integration is going anywhere. I'll have some updates coming out in the coming months. One feature to direct users to manage their Steam profile privacy to allow the pulling of data. Another to streamline the user interface to not display empty playtime in the last 2 weeks when that data is simply private, etc.
It's a challenging time for developers as we have to work with smaller and smaller data sets. But it's ultimately a good thing for your users. They have more granular control over their data.