Drew Brees has the best completion percentage in a game with 30+ passing attempts, at 96.7 percent versus the Colts on December 16, 2019.

who has the highest completion percentage in a game with at least 30 pass attempts
Interpreted as:
Who has the highest completion percentage in a regular-season game with at least 30 pass attempts?
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12/16/2019Brees10/24/2021Carr9/16/2018Carr11/11/2002Gannon12/18/2016Prescott9/13/2020Wilson10/23/2011Brees11/28/2021Tagovailoa12/14/2015Manning9/4/1983Dickey1/2/1983Anderson12/22/2019Carr9/15/2019Prescott10/12/2008Brees12/16/2007Brees9/23/2013Manning12/27/2009Brees10/11/2021Jackson10/26/2014Brady9/22/2019Ryan10/18/2009Brady12/18/2008Manning10/6/2019Watson96.791.290.689.588.988.688.687.187.187.187.186.786.786.786.786.586.586.085.785.385.385.384.8
NAMEDATETMOPPPCTATTCMPYDSAVGTDTD%INTINT%SCKSCKYRATE
Drew BreesDrew Brees12/16/2019NONOvsINDIND96.7302930710.2413.300.000148.9
Derek CarrDerek Carr10/24/2021LVLVvsPHIPHI91.234313239.525.912.900113.6
Derek CarrDerek Carr9/16/2018OAKOAK@DENDEN90.632292889.013.100.017114.6
Rich GannonRich Gannon11/11/2002OAKOAK@DENDEN89.538343529.337.900.015131.6
Dak PrescottDak Prescott12/18/2016DALDALvsTBTB88.936322797.800.000.031599.0
Russell WilsonRussell Wilson9/13/2020SEASEA@ATLATL88.635313229.2411.400.0323143.1
Drew BreesDrew Brees10/23/2011NONOvsINDIND88.635313259.3514.300.024144.9
Tua TagovailoaTua Tagovailoa11/28/2021MIAMIAvsCARCAR87.131272307.413.200.0226108.3
Eli ManningEli Manning12/14/2015NYGNYG@MIAMIA87.1312733710.9412.900.000151.5
Lynn DickeyLynn Dickey9/4/1983GBGB@HOUHOU87.1312733310.7516.113.218137.6
Ken AndersonKen Anderson1/2/1983CINCIN@HOUHOU87.1312732310.426.500.0111131.6
Derek CarrDerek Carr12/22/2019OAKOAK@LACLAC86.730262919.713.300.0324118.2
Dak PrescottDak Prescott9/15/2019DALDAL@WASWAS86.730262699.0310.013.318123.5
Drew BreesDrew Brees10/12/2008NONOvsOAKOAK86.7302632010.7310.000.011144.4
Drew BreesDrew Brees12/16/2007NONOvsARIARI86.7302631510.526.700.018132.6
Peyton ManningPeyton Manning9/23/2013DENDENvsOAKOAK86.5373237410.138.100.012135.8
Drew BreesDrew Brees12/27/2009NONOvsTBTB86.537322587.012.700.019104.7
Lamar JacksonLamar Jackson10/11/2021BALBALvsINDIND86.0433744210.349.300.025140.5
Tom BradyTom Brady10/26/2014NENEvsCHICHI85.7353035410.1514.300.000148.4
Matt RyanMatt Ryan9/22/2019ATLATL@INDIND85.334293048.938.812.900121.1
Tom BradyTom Brady10/18/2009NENEvsTENTEN85.3342938011.2617.600.026152.8
Peyton ManningPeyton Manning12/18/2008INDIND@JAXJAX85.3342936410.738.800.000140.7
Deshaun WatsonDeshaun Watson10/6/2019HOUHOUvsATLATL84.8332842612.9515.200.000158.3
Nick FolesNick Foles12/30/2018PHIPHI@WASWAS84.833282216.726.113.0312102.1
Drew BreesDrew Brees11/20/2005SDSDvsBUFBUF84.8332833910.3412.100.012149.1
Results may be incomplete. StatMuse has complete game-level data for completion percentage and passing attempts going back to the 1950 season.