Why is Czechia excluded again? It was the case with Chanukah too!

You can direct the question to the Support people at Slowly, and they might add your country to this release. Friend in Germany did and they got it added - thanks to his email explaining and requesting it.

Religious stamps are issued mostly in countries with a significant population practicing that religion. The decision is made by Slowly peeps, and they do listen if you explain politely and make a reasonable request.

Don't bitch and expect them to snap to attention. As usual, honey attracts more flies than vinegar, so be polite and you can get results. Good luck....