I looked into it further and four of the 2022 Phillies' Sunday losses thwarted a series sweep (4/10 vs. OAK, 5/15 @ LAD, 6/12 va, ARI, 6/10 @ WSH) while a fifth followed wins on a Friday and Saturday in a weekend "wraparound" series (7/10 @ STL).
And, I must correct my earlier record. The Phillies have a 5-10 record on Sundays. I overlooked that doubleheader against the Mets. But still, 25% of their losses are on Sundays. Winning percentage Monday to Saturday is .577 but on Sunday it's .333. That's a 54 win team on Sunday, a 93 win team the rest of the week. I suppose one could argue that the Phillies are what they are and Sunday--for whatever odd, crazy, stupid reason--is the day that drags them back to their statistical norm.