Your phone was lost?
No issue. Get a new one, put your seed phrase in whichever wallet you choose to install, and then. Because no other entity has access to your information, it cannot be hacked or copied.
If you lose your phone, someone might gain access to it, penetrate a weak wall of security, and get to your wallet and keys. You shouldn't recommend to people to keep using the same wallets that a 3rd-party somewhere might be trying to get into.
But even if you are the only person in possession of the keys, it's still not the best way to use the same seed across multiple wallets and devices. Why? If one of those wallets gets hacked, it's as if all your wallets got hacked because they share the same seed/keys. If one wallet turns out to have weak RNG or malicious developers who backdoor it or make it vulnerable, it's as if all your wallets are like that. Ultimately, you lose your coins. It's better to spread them out among wallets generated by trusted software/hardware on safe devices.
It's also important to stress that you should never give someone your private keys. The only access point to your blockchain assets is through your keys, which ensures their security.
Which is exactly why continuing to use a wallet whose keys are left on a phone you lost and someone else stole potentially weakens your security and makes you vulnerable to theft.