Hi Hunsa –
Thanks for reaching out! I’m sorry to hear that you are getting these warnings on your site today. It looks like these are coming specifically from the Ninja Forms plugin. It looks like the Ninja Froms plugin you are using is one we haven’t recommended in a very long time. It’s likely that the plugin is extremely out of date and I’d recommend removing it and replacing it with an alternative.
We have turned to a new forms plugin, WeForms that you could look into as a viable replacement.
I hope this helps Hunsa! Please let us know if you have any further questions for us.