If it's a recent deletion and you haven't changed anything else on your phone since your last back-up, you could try a restore. It may not work though if the last back-up was done for a major upgrade, like to ios18. Make sure you don't lose any new contacts or photos by backing them up to a cloud drive or one of those mobile back-up devices you can plug into your usb-c.
Hope this helps. Losing your passwords app can be very distressing! I sympathize with you. Not all password apps are what they should be either. Even if you can recover your old password app you should consider retiring it. If it is no longer being maintained by the developer, you will eventually lose the ability to use it in successive ios upgrades. As it is, if you need to upgrade to a new phone, you will likely not be able to use it on the new os. If you recover your password app, you should select a new one from the app store anyway and start moving your passwords to the new app.
I don't use the popular apps because the back-ups they offer are always by subscription and the data is sometimes not properly secured. This holds your information hostage if for any reason you are no longer able to pay the subscription. If you are comfortable with Apple hosting your password information, just use the one they offer, assuming your phone has a recent ios. Otherwise, I am biased toward Zetetic's Codebook (uses military grade encryption, very customizable). Always up to date, extremely fast, excellent support, available on most platforms (including MAC and Windows), has manually sync to your computer, as well as Dropbox or Google Drive. They also offer a paid subscription to their new Codebook Cloud auto-sync, so you don't even have to think about it. Zetetic has a long history in the password vault industry, and very fast, excellent support. Best of all, they have a one-time fee. And no, I don't work for them, but I have used their apps for over 20 years.
