Since wp 5.9 the contact form 7 block is not working properly. (fresh installation, twentytwentyone and no plugins)
Either you can’t edit your page anymore (blank screen, see console underneath) or you get an failed block with “this block encountered an error and cannot be previewed”
Workaround: Just use the shortcode block
react-dom.min.js?ver=17.0.1:141 TypeError: Cannot read properties of undefined (reading '0')
at save (index.js?ver=5.5.4:1:4122)
at yt (blocks.min.js?ver=28d5b8f8805a22435cbdc51927067812:2:27409)
at wt (blocks.min.js?ver=28d5b8f8805a22435cbdc51927067812:2:27802)
at blocks.min.js?ver=28d5b8f8805a22435cbdc51927067812:2:54385
at Br (blocks.min.js?ver=28d5b8f8805a22435cbdc51927067812:2:54531)
at Nr (blocks.min.js?ver=28d5b8f8805a22435cbdc51927067812:2:55473)
at blocks.min.js?ver=28d5b8f8805a22435cbdc51927067812:2:56486
at Array.reduce (<anonymous>)
at Ar (blocks.min.js?ver=28d5b8f8805a22435cbdc51927067812:2:56463)
at core-data.min.js?ver=b4684a7c90f2d858ab7fa74414ad5a54:2:44258