This is reported by Reuters, referring to the Finnish operator Gasgrid.
Finland refused to comply with Moscow's demand to pay for gas with Gazprombank's conversion of foreign currency into rubles. Bulgaria and Poland have already been cut off from deliveries - both countries also failed to comply with Russian requirements.
Note that Finland has been using Russian gas for half a century.
Gasum indicated that they were going to supply Finnish customers through the Balticconnector gas pipeline. This gas pipeline connects the gas transmission systems of Finland and Estonia along the bottom of the Gulf of Finland.
The day before it became known that the Russian company would no longer supply Gasum fuel until payment was received in rubles: as of May 20 (the payment deadline stipulated by the contract), the Russian company had not received payment from the Finnish side. On the same day, Gazprom Export promised to sue the Finnish side in an arbitration court.