Here are the BIP-173 test vectors,
https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki#user-content-Checksum_design
If I drop those into the demo page here,
https://slowli.github.io/bech32-buffer
The inputs decode into the wrong values.
One example, this input : BC1SW50QA3JX3S
BIP-173 says it should decode into 6002751e
The Bech32 Demo page decodes that string into 83a8f0