https://old.reddit.com/r/git/comments/59j0yq/gitkraken_is_no...
On top of that GitKraken is closed-source and in the past there were concerns on telemetry collection: https://old.reddit.com/r/git/comments/4dgpgd/gitkraken_data_...
Nothing major, which is why I am still using it, but definitely enough to make you wary.