I like Leftwich. When you have Tom Brady though you have to use him, in both 2020 and 2021 he threw 40+ TDs (only 2021 was a 17 game season but he threw 40 in the first 16 games, 43 total). The only other time he crossed that mark in his 23 seasons was the 18-1 season with Moss. And 2019 was probably Winston's best season as a QB despite the ints.
In the 2020 season he had a near 1000 yard rusher in Ronald Jones (978 yards) and Fournette as the 1-2 punch with near 100 carries of his own, so it wasn't completely neglected - actually combined for more carries in that 16 game season than our 2 backs had this year. Their roles switched in 2021 with Fournette having the bulk of carries and Jones as the #2. 2022 had Brady retire and unretire, Arians retire and Jones left in FA as well so it's not a complete surprise they didn't have their best year. But they did win the division (with an 8-9 record! Actually, just looking, the Bucs have gone 8-9, 9-8, and 10-7 in the last 3 years and we've gone 9-8 9-8 10-7... but they have 3 division titles

), and Brady at age 45 still had an OK season with 25 TDs and 9 INTs.
I agree it would be questionable if he was still going too pass heavy, but you make use of the tools you have and he had the finest QB tool available so yeah you make use of him.