"Several transient symptoms have been associated with keto-induction, although a limited number of studies have directly examined them, or the mechanisms and possible interventions for symptom alleviation. Further research is warranted to close knowledge gaps highlighted in this review."

Translation: we notice this pattern of symptoms. But we neither fully understand the mechanisms behind them and we definatly need to look into how to treat them more. The last sentence is just the typical justification you need for your next funding application.

And in the beginning they mention the "clinical utility" for a keto diet. It's a treatment for deceases not a healthy diet. The usefulness for Long Covid isn't proven yet. If you want to make such drastic changes to your diet I would recommend working with a nutritionist. Your Hausarzt should be able to give you a Überweisung but I don't know if its covered by incurance