The form of tax evasion is wrong declaration of earnings.
This means intentionally reporting an incorrect amount of income to the government in order to pay less taxes or avoid paying taxes altogether. For example, someone might fail to report all of the income they earned from their job, or they might overstate their deductions in order to reduce their taxable income. This is illegal and can result in penalties or even criminal charges.
Payment of flat rate tax, constant change of employment, and low capacity utilization are not necessarily forms of tax evasion. Flat rate tax is a legitimate tax system where everyone pays the same rate regardless of their income level. Constant change of employment and low capacity utilization may have tax implications, but they are not inherently illegal or fraudulent.