Do they evaluate this kind of tax implementation through adding taxes was based on a standard business taxable income? If not I guess that's not fair to a gambling institution, since they're also into competition with other business who's running gambling. Though gambling using cryptocurrency currency was in demand by most online players, they shouldn't take advantage of that specially during a situation of pandemic.
I am sure the government already study of what is happening to their country, so if they want to add more taxes, they will calculate or simulate everything necessary. They have experts that can evaluate, calculate or other things that could happen during the implementations. Even if we think it is not fair for them, the business owner tries to obey what the government wants, and if they object to the tax implementation, they can ask to get relief.
Perhaps, that is what the offline business, including the gambling business, can do regarding the additional taxes that will apply in their country. The government will try to be fair for all business owners because they helped the country run by paying taxes.