My MacBook Pro 2017. After decryption is still stuck on login screen and says your Mac is decrypted

changing the setting for decryption takes about a minute.

But what they don't 'club you on the head' with is that the actual process of encrypting/decrypting a drive will take place in the background, over many hours, and possibly not complete for a day or more. This background process only make progress when your Mac is not overly busy, and when it is awake.

You can use your Mac for most purposes while it is transitioning, and it will compensate. There are a few things you can NOT do until it complete, including change your mind, and install new software.

can you enter your password? what happens when you do?

That message is confusing. When you see that exact screen, your computer restarted AT THIS MOMENT because of a problem, not long ago.

You entered your password, THEN your computer crashed and has to Restart.

Try using safe mode, by holding the shift key at startup. This will perform a disk repair during startup, so it takes a few minutes longer. No third-party add-ons are loaded in safe mode.

You could also try to enter recovery and use Disk Utility to repair the disk. Your Intel Mac 2017 does not have a T2 chip.