text: Title: Visual glitches with thick line(>1) on version 0.12.4
  Body: <!-- In the following, please describe your issue in detail! -->
  <!-- If some of the sections do not apply, just remove them. -->
  
  ### Short description
  When setting line width thicker than 1, zooming in causes some line to fill up a large area
  https://user-images.githubusercontent.com/66480156/156883464-b96a4b43-101e-46aa-afed-2ff300aae082.mp4
  
  ### Code to reproduce
  That light green line was created this way
  ```python
  import pyqtgraph as pyqtgraph
  plot_item = pyqtgraph.PlotItem()
  line = plot_item.plot(
      pen=pyqtgraph.mkPen("#E2F200", width=2.5),
      connect="finite",
  ),
  ```
  
  ### Expected behavior
  Zooming in normally
  
  ### Real behavior
  Light green line fills up a large space. No error occured.
  
  ### Tested environment(s)
   * PyQtGraph version: 0.12.4
   * Qt Python binding: Pyside6 6.2.3 Qt 6.2.3
   * Python version: 3.10.2
   * NumPy version: 1.22.2
   * Operating system:  Windows 11
   * Installation method: pip
  
  ### Additional context
  None
  