It's not secure at all, as some services (PayPal!) Allow password reset via SMS to your regitered mobile number. So if someone even has control of your mobile number via sim swap for 5 minutes they gain full control of your paypal acct. Heard of enough incidents of this earlier this year through one of the Canadian prepaid mobile flanker brands...

Paypal makes it hard to remove a mobile number from your account once it's on there too...

If a bank "MUST" have a phone number, I lean towards providing my good ol landline number since in theory thats a "little" harder to instantly take over or port out.

Worthwhile to "test" what it takes to reset a password on your various critical services...