From the JSON, this is the key part:
"emailMessage/To": null
If Recipients Email is a SharePoint Person column, make sure you are not using the main field value. You need to use the email property from that field, usually something like Recipients Email Email.
If the field allows multiple people, Power Automate treats it as an array, so you need to convert the selected people into one email string before the email action. A simple way is to use a Select action to pull out each person’s email address, then use this in the To field:
join(body('Select'), ';')
That should give the email action something like:
user1@company.com;user2@company.com
Also worth checking that the SharePoint item definitely has someone selected in that field before the email step runs. If the field is blank on the item, Power Automate will still pass null.
