What is the test for establishing an unfair advantage of one spouse under section 721 of the California Marriage Act?

any unfair advantage of the other. [Citation.] Thus, "[i]f one spouse secures an advantage from the transaction, a statutory presumption arises under section 721 that the advantaged spouse exercised undue influence and the transaction will be set aside." [Citation.] An advantage results to one spouse when that spouse gains or when the other spouse is hurt by the transaction." ( Lintz v. Lintz (2014) 222 Cal.App.4th 1346, 1353, 167 Cal.Rptr.3d 50.) "The presumption is rebuttable; the spouse advantaged by the transaction must establish that the disadvantaged spouse acted freely and

[39 Cal.App.5th 1041]