The poll you're referencing was run Sept 7-12 by OH Predictive Insights. Until last year, OHPI had a habit of overestimating support for Republicans, and the movement of their polls in 2020 suggests they were doing some grouping in the runup to election day, so it's reasonable to assume they've got a degree of conservative bias.

u/caseCo825 is referencing a more recent poll from Morning Consult, which shows Sinema with 42% positive/42% negative. Morning Consult overestimates support for Democratic candidates more frequently than it does Republicans, indicating a liberal bias.

Given the polls' respective biases and margins of error, they're really not that far apart.

However the time difference involved, and comparative movement, is worth noting. OHPI's poll, conducted before Sinema's current cycle in the political spotlight, showed her unfavorability among Democrats to be nearly identical to what it was in March of this year. Morning Consult's, conducted after she started blocking the reconciliation bill, shows a marked uptick in unfavorability among Democrats.