If someone makes a will in your name and signs this themselves or tricks you into signing a will then this would be a case of fraud. Fraud is illegal and if you suspect you may be a victim of fraud then you should contact the police when it is safe to do so.
If you suspect that this may have happened but you aren’t certain you can make a new will or update your will as soon as safe to do so. You should ensure that the will is securely stored out of harm’s way e.g. with the National Will Safe and inform the executors. For additional peace of mind you might choose to appoint a professional executor.
You should also consider speaking with a traditional solicitor to protect your wishes.