Since 2018-19, Gregg Popovich has lost the most games by a coach, with 280 losses.

Interpreted as:

most regular-season losses NBA coaches since 2019

COACH	L	GP	MPG	PPG	RPG	APG	SPG	BPG	TPG	FGM	FGA	FG%	3PM	3PA	3P%	FTM	FTA	FT%	MIN	PTS	REB	AST	STL	BLK	TOV	PF
Gregg Popovich	280	471	242.0	112.5	44.4	26.5	7.0	5.1	12.8	42.5	90.8	46.8	11.0	30.5	35.9	16.7	21.3	78.3	113,990	52,992	20,922	12,493	3,306	2,387	6,043	8,684
Dwane Casey	263	384	241.8	107.2	43.0	23.4	7.3	4.4	13.9	38.9	87.1	44.6	11.7	33.5	34.7	17.8	23.3	76.1	92,835	41,173	16,521	8,985	2,794	1,702	5,329	8,199
Rick Carlisle	250	475	241.3	114.9	43.7	25.7	6.9	5.1	12.9	42.0	89.4	47.0	13.4	37.2	35.9	17.5	22.7	77.2	114,600	54,584	20,765	12,230	3,286	2,442	6,129	9,680
Steve Clifford	247	391	241.0	107.3	44.0	24.3	7.2	5.0	12.8	39.9	88.9	44.9	11.2	32.6	34.5	16.2	21.0	77.2	94,240	41,957	17,200	9,508	2,834	1,955	4,993	7,232
Billy Donovan	223	472	242.1	112.2	44.1	24.2	7.8	4.6	12.9	41.9	88.6	47.3	11.2	31.0	36.0	17.2	22.0	78.3	114,280	52,940	20,804	11,418	3,665	2,183	6,092	9,223
Steve Kerr	211	465	241.3	114.5	44.9	28.3	7.8	4.8	14.4	42.0	89.1	47.2	14.1	37.9	37.3	16.4	20.8	78.8	112,225	53,261	20,887	13,138	3,625	2,238	6,697	9,665
J.B. Bickerstaff	208	411	241.9	108.2	42.6	25.3	7.5	4.7	13.3	40.0	85.4	46.8	11.4	32.0	35.5	16.9	22.1	76.4	99,415	44,463	17,523	10,380	3,091	1,917	5,449	7,735
Erik Spoelstra	207	473	241.6	109.2	43.1	25.2	7.7	3.9	13.3	39.5	85.4	46.3	12.6	34.7	36.3	17.6	22.4	78.8	114,270	51,659	20,409	11,939	3,621	1,854	6,274	9,186
Nick Nurse	198	472	241.5	112.6	43.9	24.3	8.8	5.2	12.3	41.1	89.7	45.8	12.5	34.8	35.9	17.9	22.5	79.7	114,005	53,134	20,735	11,447	4,138	2,475	5,801	9,725
Taylor Jenkins	185	391	241.2	112.8	46.3	26.1	8.7	5.8	13.4	42.2	91.5	46.1	11.8	33.6	35.0	16.7	22.2	75.1	94,315	44,123	18,092	10,194	3,384	2,269	5,230	7,721
Monty Williams	183	391	241.3	113.4	43.9	26.8	7.4	4.5	13.2	42.2	89.0	47.4	11.8	32.5	36.4	17.1	21.2	80.7	94,340	44,339	17,164	10,493	2,894	1,777	5,169	8,043
Stephen Silas	177	236	240.7	109.8	43.7	23.2	7.4	4.7	15.2	39.8	87.9	45.2	12.5	36.9	33.9	17.8	24.1	73.6	56,815	25,911	10,308	5,466	1,746	1,117	3,576	4,778
Mark Daigneault	175	318	241.6	111.8	44.2	24.0	7.8	5.0	13.2	41.3	89.8	45.9	12.4	35.2	35.1	16.9	21.6	78.1	76,820	35,546	14,050	7,635	2,496	1,575	4,189	6,069
Quin Snyder	170	412	241.2	114.8	46.1	24.4	7.1	4.9	13.7	41.3	88.0	47.0	13.9	37.6	36.9	18.2	23.4	77.6	99,380	47,283	18,979	10,033	2,940	2,019	5,631	7,998
Michael Malone	168	473	241.5	113.4	44.4	27.9	7.6	4.6	13.0	42.8	88.2	48.4	11.8	32.4	36.5	16.1	20.8	77.3	114,220	53,639	21,014	13,191	3,597	2,153	6,168	9,156
Chauncey Billups	165	246	241.2	108.7	42.1	23.4	7.5	4.5	13.9	39.5	87.4	45.1	12.3	35.1	35.2	17.4	22.2	78.3	59,340	26,732	10,345	5,755	1,837	1,096	3,424	5,025
Tom Thibodeau	164	358	241.7	110.8	45.6	22.9	7.2	4.7	12.3	40.2	88.0	45.7	12.4	34.1	36.5	17.9	23.3	76.9	86,545	39,655	16,334	8,197	2,581	1,666	4,394	7,066
James Borrego	163	301	241.9	110.0	43.8	25.5	7.6	4.7	13.0	40.2	88.9	45.2	12.9	35.9	36.0	16.6	21.8	76.3	72,815	33,106	13,179	7,689	2,291	1,419	3,922	5,700
Doc Rivers	158	425	241.8	113.8	44.1	24.3	7.6	5.1	13.1	40.9	86.3	47.3	11.8	31.4	37.5	20.3	25.4	79.9	102,775	48,364	18,748	10,312	3,240	2,153	5,560	8,846
Jamahl Mosley	143	246	241.2	108.7	43.3	23.9	7.4	4.8	14.0	39.8	86.5	46.0	11.3	33.1	34.2	17.9	23.0	77.6	59,340	26,741	10,646	5,876	1,827	1,172	3,440	4,882
Nate McMillan	142	334	241.0	112.0	43.6	25.1	7.5	4.8	12.3	42.1	88.6	47.5	11.0	29.9	36.9	16.8	21.2	79.2	80,510	37,397	14,576	8,400	2,520	1,597	4,114	6,414
Tyronn Lue	140	324	240.8	112.7	43.6	24.4	7.3	4.6	12.8	41.3	86.8	47.6	12.9	33.6	38.5	17.2	21.3	80.8	78,035	36,528	14,117	7,904	2,376	1,487	4,162	6,166
Luke Walton	138	243	241.2	111.7	43.7	24.8	7.6	4.8	14.0	41.9	89.3	47.0	11.7	33.1	35.2	16.1	21.9	73.7	58,620	27,135	10,623	6,026	1,839	1,176	3,392	5,026
Scott Brooks	135	226	242.0	115.0	43.2	25.6	7.9	4.4	13.7	42.3	90.6	46.7	11.2	31.7	35.3	19.3	24.9	77.5	54,690	25,986	9,754	5,790	1,785	985	3,098	4,890
Frank Vogel	131	307	242.0	112.9	44.5	25.3	7.9	5.8	14.3	41.8	87.3	47.8	11.7	32.5	35.8	17.7	23.5	75.3	74,305	34,665	13,653	7,764	2,410	1,772	4,395	5,977