[False Negative]:

### What bug did Slither miss and which detector did you anticipate would catch it?

Can't judge that it's a proxy contract.
https://etherscan.io/address/0x1111111254EEB25477B68fb85Ed929f73A960582

### Frequency

Very Frequently

### Code example to reproduce the issue:

for contract in self.contracts:
if contract.is_upgradeable:`

### Version:

0.9.6

### Relevant log output:

_No response_