These films are available free worldwide with English subtitles at least through 30 June 2022 at 35mm.online/en/. When it finally ends it looks like the films will still be available for a subscription fee.
The site also includes shorts, animation, & documentaries, but those are not included on this list.
Films added March 2022:
The Hourglass Sanatorium
Man of Marble
Hospital of the Transfiguration
Man of Iron
added April 2022:
Knights of the Teutonic Order
added May 2022 (5 films by Juliusz Machulski):
Va Banque II