LaTeX: Empty cells create extra row height

Describe the bug

When adding an empty cell in a table with \ , the pdflatex target creates a row with extra (double) height. This does not happen if the cell is truly empty (just spaces), but this doesn't work for the first cell in a row. For example:

Table example
=============

======== ======== ========
Foo      Bar      Meh
-------- -------- --------
1.234    4.567    7.890
======== ======== ========

======== ======== ========
\        Bar      Meh
-------- -------- --------
1.234    4.567    7.890
======== ======== ========

======== ======== ========
         Bar      Meh
-------- -------- --------
1.234    4.567    7.890
======== ======== ========

The first table is fine. The second table has the top left cell empty and gets double height in the PDF. The third table shows what happens if the \ is not used here. And the result:

How to Reproduce

Just a default project with the file shown above should work. Then make latexpdf.

Expected behavior

The row heights of the second table should be the same as in the first one.

Your project

N/A

Screenshots

No response

OS

Kubuntu 18.04

Python version

3.6.9

Sphinx version

4.5.0

Sphinx extensions

No response

Extra tools

No response

Additional context

No response

Reproduce the issue in a default project using the table shown in the report, then run make latexpdf and compare the three generated table layouts. Trace the LaTeX output for the empty first cell and determine why \ adds extra row height. Done means the second table has the same row heights as the first.