Does compensation which is due to workers during their isolation as persons infected with, suspected of being infected with, or suspected of being contagious with COVID-19 for the pecuniary disadvantages caused by the impediment to their employment, and which is initially payable to the workers by their employer, with the entitlement to compensation vis-à-vis the Austrian Federal Government then being transferred to the employer at the time of payment, constitute a sickness benefit within the meaning of Article 3(1)(a) of Regulation (EC) No 883/2004?

If Question 1 is answered in the negative: Must Article 45 TFEU and Article 7 of Regulation (EU) No 492/2011 be interpreted as precluding national legislation under which the granting of compensation for loss of earnings suffered by workers as a result of isolation ordered by the health authorities in the case of a positive COVID-19 test result (with the compensation being initially payable to the workers by their employer, and the entitlement to compensation vis-à-vis the Austrian Federal Government then being transferred to the employer to that extent) is subject to the condition that the isolation is ordered by an Austrian authority on the basis of provisions of national law relating to epidemics, with the result that such compensation is not paid to workers who, as frontier workers, are resident in another Member State and whose isolation (‘quarantine’) is ordered by the health authorities of their Member State of residence?