That watermark is idiot-insurance so that clients don't later look at their copy of the returns, panic and think that if they [the client] have them that the IRS doesn't, and then mail them in to the IRS.

Laugh all you want, but it's truly amazing the panic clients can get themselves into not understanding how this all works. I get a few "don't file yet! I found one more form! is it too late?!?" when I haven't even sent the DocuSign. And also a few "When are we filing?" after I've sent them confirmations of successful e-file.

For clients that complain about the watermark, tell them it's put on by your software.

FWIW, I put a PDF of the Client Copy no watermark in TaxDome for them with SSNs redacted (because clients are not careful with their own PII once it's in their downloads folder). That way they have a "pretty" one if it's so desperately needed.