So Greece will pay for Russian gas in rubles via the Gazprombank Exchange, and Bulgaria will continue receive Russian gas through the back door from Greece.
Very similar to how Poland continues to get Russian gas from Germany.
Poland from October will not get any Russian gas, even indirectly.
The gas from Germany is a stop gap.
Poland had already prepared to be using norway gas and imported American gas from December when the gazprom contract ended. However Russia, being the bad faith supplier, decided to default on the contract terms earlier.
Ditto for Bulgaria, they will import gas from Azerbaijan via Greece.
Greece is paying for Russian gas in euros.