immigration is very good for economic growth
This is certainly true for US-style immigration, where immigrants are higher-skilled and likely to speak English. But surely the effect is comparatively worse for European-style immigration, where immigrants tend to be much poorer, often refugees from religious third-world countries, and have a low chance of speaking the native language. All of which complicates integration and increases anti-immigration sentiment.
I found that event online, but not the claim that this was what motivated the shift in policy.