Restaurant services - Goods and Services Tax - GST

In case of restaurant services, if they opt for 5% rate of GST for outward supplies by virtue of Notification No. 20/2019- Central Tax (Rate). They are not eligible for availment of ITC as per the notification. But however, if inadvertenly they have availed an ITC say for 2 months and subsequently found out the same and reversed the ITC along with interest. Can they still continue in 5% rate of tax or because they have availed inadvertenly ITC for 2 months and subseqently reversed the same, the benefit of 5% does not applicable to them and subsequently apply 18% on outward supply.