Is filling the bathtub with water and bathing in it considered extravagance and a violation of the Sunnah? And is an employee excused who signs in and then leaves due to a psychological illness, and does giving charity for the days of his absence clear his conscience from the money he took?

The limit of extravagance in water usage is when the purifier uses water beyond what is legally necessary. Muslims have unanimously agreed that the sufficient amount of water for ablution (wudu) and ritual bath (ghusl (definition)) is not fixed. The focus is on proficiency, and it varies according to different bodies. What is mentioned in the Hadith (definition), "Ghusl is a sa', and wudu is a mudd," applies to those whose body is like that of the Prophet, peace and blessings be upon him; otherwise, it varies according to need.

As for a worker's dereliction of duty, it is not permissible and constitutes a neglect of responsibility and a betrayal of trust. If the employer permits it, there is no sin upon him. If he does not permit it, then it is not lawful for him to be remiss. Psychological illness may lift the sin if he is overcome by it. He must compensate the responsible party for what he neglected in his work, unless they absolve him.