If your QSEHRA is structured correctly, it can operate alongside an employee HSA. As long as your QSEHRA is ‘limited-purpose’, then employees are allowed to receive both HRA reimbursements and HSA contributions.
Limited-purpose QSEHRAs are limited to reimburse the cost of health insurance premiums, preventive care, dental, vision, and long-term care premiums. This is actually very common for small business QSEHRAs, which often are employer-limited to only reimburse the cost of employee premiums.