From @AndyL report:
Common means I can reproduce the issues on both Windows 10 21H1 and Windows 10 1909.
Issue 1.1 - Cursor in the wrong place when inserting between symbols and texts
To reproduce:
- Type some bold texts and then type some regular texts (such as:
**Bold**Regular Texts)
- Place the cursor after the last
* and before the first regular text(R)
- Press and hold
,(please use Chinese IME)

You can see that the cursor is in the wrong place.
For Issue 1.1, if you use source mode, then it will be solved.
Issue 1.2 - Cursor in the wrong place when editing headers
To reproduce:
- Turn on the Editor setting - Collapse Heading
- Type a markdown header (such as:
#### Header) and make sure there should be some texts below the heading
- Select the
#### (with space) part
- Type
, (please use Chinese IME)

You can see that the cursor is in the wrong place (again).
For Issue 1.2, if you turn off Collapse Heading, then it will be solved.
Issue 1.3 - Punctuation gets selected
To reproduce:
- Type some bold texts (such as
**Bold**) and add a line below it
- Place the cursor after the last
* and press ,(please use Chinese IME) for several
times

You can see that the second , is selected.
For Issue 1.3, if you use source mode, then it will be solved.