The default text inserted for a pasted image doesn’t interact well with tables.
The pipe symbol in the markdown below:

Gets wrongly interpreted as a column separator. When pasting an image into a table, you get this:
|col A|col B|col C|
|---|---|---|
|hello| | |
col A | col B | col C |
---|---|---|
hello |  |
You can work around it by either removing the image sizing information or escaping it:
|col A|col B|col C|
|---|---|---|
|hello| | |
|there| | |
col A | col B | col C |
---|---|---|
hello | ![]() |
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there | ![]() |
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