which files

grep -LR '^tags: ' content/everblog | grep ".md$"

single file fix

sed '/^---$/,/^---$/s/^$/tags: []\ndraft: true/' content/everblog/opinion-stop-wasting-a-perfectly-good-bug.md

merge

echo 'content/everblog/insight-heroes-journey-why.md' | xargs -I {} sed '/^---$/,/^---$/s/^$/tags: []\ndraft: true/' {}

Speedrun

grep -LR '^tags: ' content/blog | grep ".md$" | xargs -I {} sed -i "" '/^---$/,/^---$/s/^$/tags: []\ndraft: true/' {}