Is my absence from work and signing for days I did not attend permissible, and what is the ruling on the salaries I received during the period of absence, and should I continue in this manner?

Signing in as present while absent is forbidden due to it encompassing lying and consuming people's wealth unjustly. The salaries received for these days must be returned to the employer because it is ill-gotten gain that cannot be benefited from or given as charity. Likewise, it is not permissible to continue being absent while signing in as present. A Muslim must fulfill the trust in their work and beware of betrayal.