Here you have (albeit small) proof of some sort of trend: https://trends.google.com/explore?q=codeberg%2Cforgejo%2Cgit...
Still, doesn't come close to popularity of GitHub itself today (https://trends.google.com/explore?q=codeberg%2Cforgejo%2Cgit...), but I think the trend of moving away from GitHub is clear both in data and sentiment, both qualitative and quantitative.
The trend i see in Google is explosion in git(hub) related searches and small blip in non-github alternatives
If only the article used any of that. And if it did, I still don't think the headline was warranted.
Also Google search trends are no evidence of adoption or migration. High chance of correlation, sure.