I encrypted my file a few years ago on my linux debian computer, I do not use this comp now.
Was the computer permanently airgapped when you did it? Did you delete the temporary files and over write the relevant sectors of your hard disk, or destroyed the hard drive?
I have only this encrypted file in my phone and in two usb sticks that are in a metal safe, and I have learnt my seed by heart.
Why is it on your phone at all? Do you ever decrypt it on your phone? Can you vouch for every single app, download, piece of software, etc., on your phone that none of them have any malicious code in them whatsoever?
Everything else is paranoia...
Maybe. But keeping a digital back up secure is exponentially harder than keeping a paper back up secure. The number of people who have thought their digital back was secure and ended up being compromised and having all their coins stolen is orders of magnitudes higher than people who have had a paper back up compromised and had all their coins stolen.
When there are two options of achieving the same outcome (backing up your seed phrase), why would you ever choose the riskier of the two?