Add a signature causes a '1 page(s) Modified', but the signature is valid

[Vincent27500992cbzw]

When I add a signature, in the signature panel, the signature is valid, but there exists a warining: '1 page(s) Modified'. I want to know：

1. When will this warning appear?

2. How can I avoid this warning？

3.If I set all the text fields is "Readonly", will this warning disappear?

[MikelKlink]

Can you share the signed PDF in question for analysis? If there are information in it that are not for public consumption, please try to reproduce the issue with a PDF that can be shared.