First, the actual battle lines currently are inside of Kherson and Zaporizhzhia. This deal backs those up meaning Russia concedes territory it already holds, and Ukraine concedes no territory at all.  You might think Ukraine's pre-2022 borders are the 'proper' borders but Russia thinks Ukraine's pre-Soviet breakup are the 'proper' borders.  Ukraine arguing from it's memory of "we used to hold this land" is just as illogical as Russia arguing from it's memory of "we used to hold this land".  The only real objective truth is the current battle lines, and this agreement favors Ukraine decisively in that regard.