You were lucky to have your funds back but the highlighted part in your post is the worst way to backup your seed phrase as having Screenshot in your mobile phone is as risky as telling them to people openly.The first rule is i would say offline storage on piece of paper or metal sheets with full safety.What if your phone was lost, stolen or damaged would you be able to get your funds back then and it would be permanently lost adding up to the shrinking supply of 21million.
I can think of worse ways of storing a backup for example storing them online via pastebin or something would be absolutely disastrous, but yeah it definitely isn't optimal, far from it. Not only from the malicious attackers point of view, but also phones are easily damaged. I don't know how many phones I've gone through over the years. Only takes water damage or a drop or two, and your data could be gone. There's many ways of backing up a seed, you could go the washer route which is probably a little over kill for most users, but as long as your storing it offline in a reasonably secure place, then you should be fine.
