Please note: My initial interpretation of the CGPath differences in the 'Evidence: CGPath Analysis' section below seems to have been based on a misunderstanding of the exact path changes.
To provide a more precise analysis and ensure clarity, I'm re-attaching the full po {shadowPath} output for both cases below.
Original Path Descriptions
Here are the original Path descriptions you provided, which were used for the analysis.
Path 1: Path for Height = 48.7 (Expected Behavior)
Path 0x60000300a0a0:
moveto (24.4586, 0)
lineto (24.5414, 0)
curveto (31.5841, 0) (35.1055, 0) (38.8961, 1.19858)
lineto (38.8961, 1.19858)
curveto (43.0348, 2.70495) (46.295, 5.96518) (47.8014, 10.1039)
curveto (49, 13.8945) (49, 17.4159) (49, 24.4586)
lineto (49, 325.541)
curveto (49, 332.584) (49, 336.105) (47.8014, 339.896)
lineto (47.8014, 339.896)
curveto (46.295, 344.035) (43.0348, 347.295) (38.8961, 348.801)
curveto (35.1055, 350) (31.5841, 350) (24.5414, 350)
lineto (24.4586, 350)
curveto (17.4159, 350) (13.8945, 350) (10.1039, 348.801)
lineto (10.1039, 348.801)
curveto (5.96518, 347.295) (2.70495, 344.035) (1.19858, 339.896)
curveto (0, 336.105) (0, 332.584) (0, 325.541)
lineto (0, 24.4586)
curveto (0, 17.4159) (0, 13.8945) (1.19858, 10.1039)
lineto (1.19858, 10.1039)
curveto (2.70495, 5.96518) (5.96518, 2.70495) (10.1039, 1.19858)
curveto (13.8945, 0) (17.4159, 0) (24.4586, 0)
lineto (24.4586, 0)
Path 2: Path for Height = 48.6 (Anomalous Behavior)
Path 0x600003028630:
moveto (24.1667, 0)
lineto (24.1667, 0)
curveto (24.1667, 0) (24.1667, 0) (24.1667, 0)
lineto (25.375, 1.44329e-15)
curveto (34.8362, -2.77556e-16) (43.2871, 5.9174) (46.523, 14.808)
curveto (48.3333, 20.5334) (48.3333, 25.8521) (48.3333, 36.4896)
lineto (48.3333, 325.541)
curveto (48.3333, 324.148) (48.3333, 329.467) (46.523, 335.192)
lineto (46.523, 335.192)
curveto (43.2871, 344.083) (34.8362, 350) (25.375, 350)
curveto (24.1667, 350) (24.1667, 350) (24.1667, 350)
lineto (24.1667, 350)
curveto (24.1667, 350) (24.1667, 350) (24.1667, 350)
lineto (22.9583, 350)
curveto (13.4972, 350) (5.04626, 344.083) (1.81036, 335.192)
curveto (0, 329.467) (0, 324.148) (0, 313.51)
lineto (0, 24.4586)
curveto (0, 25.8521) (0, 20.5334) (1.81036, 14.808)
lineto (1.81036, 14.808)
curveto (5.04626, 5.9174) (13.4972, 3.16414e-15) (22.9583, 1.44329e-15)
curveto (24.1667, 0) (24.1667, 0) (24.1667, 0)
lineto (24.1667, 0)
Topic:
UI Frameworks
SubTopic:
UIKit
Tags: