Project Config rebuild creates inconsistencies

I know this has been mentioned in a few issues, but I wanted to document a good couple of issues that would be great to resolve. Each time we rebuild the project config for projects, we find there are oodles of changes, which kind of freaks me out.

Most are harmless, but the constant level of change means that we can easily overlook potentially incorrect changes or bugs. If there are always harmless changes we get used to just committing everything blindly, which isn't great.

Below are some examples:

Type changes, including integers and booleans. See https://github.com/craftcms/cms/issues/6979

field: 2642eb7b-2a92-4acf-9bb7-68adaf91310f
name: Columns
-sortOrder: 25
+sortOrder: '25'

-required: '0'
+sortOrder: false

settings:
-  default: ''
+  default: false

-titleFormat: ''
+titleFormat: null

Array changes, seems to expand serialised arrays sometimes

-childBlocks:
-  - card
+childBlocks: '["card"]'
field: 2642eb7b-2a92-4acf-9bb7-68adaf91310f
fieldLayouts:
-  -
+  085c0254-f2ed-48f8-b8cc-915776480da8:
    tabs:
      -
        elements:
          -
            fieldUid: e2dcbd9e-0478-40ec-886a-b7210d695a22
            instructions: null
            label: null

enableVersioning: true
handle: news
name: News
previewTargets:
  -
-    label: 'Primary entry page'
-    urlFormat: '{url}'
+    __assoc__:
+      -
+        - label
+        - 'Primary entry page'
+      -
+        - urlFormat
+        - '{url}'
+      -
+        - refresh
+        - '1'
propagationMethod: all
siteSettings:
  011ae8e8-6cf1-434b-a64f-bd430fc3354b:
    enabledByDefault: true
    hasUrls: true
    template: news/_entry
    uriFormat: 'news/{postDate.year}/{slug}'

User Photos asset volume's field layout keeps getting re-created each time I run rebuild, despite not touching it at all.

userPhotos--a35713a1-7237-49a1-ac3e-0fa1d1b5bded.yaml

fieldLayouts:
-  f8017d72-d47a-4715-91de-93ef22515ee4:
+  ea9c4d86-95af-453d-bb31-6e7fe48f7953:
    tabs:
      -
        elements:
          -
            autocapitalize: true
            autocomplete: false
            autocorrect: true

fieldLayouts:
-  ea9c4d86-95af-453d-bb31-6e7fe48f7953:
+  b8889af8-68ce-444e-b4d5-1c6d1585d6c9:
    tabs:
      -
        elements:
          -
            autocapitalize: true
            autocomplete: false
            autocorrect: true

This can be pretty consistently reproduced by saving a section or a field, which will trigger any of the above changes to the yaml files. Then, triggering a project config rebuild will trigger more changes - just feels like it's always changing!

There's probably more examples, and I'll add them as I come across them.

Additional info

• Craft version: 3.5.15.1
• PHP version: 7.2
• Database driver & version: MySQL 5.7.30

Reproduce the issue by saving a section or field, then rebuilding the project config and comparing the generated YAML. Start with the named userPhotos--a35713a1-7237-49a1-ac3e-0fa1d1b5bded.yaml file and the listed type, array, and field-layout changes; done means repeated rebuilds no longer introduce unintended differences.