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.
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.
The trend i see in Google is explosion in git(hub) related searches and small blip in non-github alternatives