QTextEdit with Consolas font: a line that ends with Hindi characters breaks the font of the next line

This bug can be reproduced in all versions which I tried, including Qt 5.15 and Qt 6.

The simplest way to reproduce it does not even require creating any projects or writing C++ code:
1) open Qt Designer;
2) create a new Widget;
3) insert a new QTextEdit into that Widget, set its font to Consolas, assign the following HTML to it: (see "html_1.txt" in the attachments).

Actual result: the spaces on the line after the one with Hindi characters get shrunk; the font of that line seems to be reset to some other one instead of Consolas (see the attached screenshot "qtbug_1.png").

Expected result: same offsets on all lines which contain 4 spaces at their beginning; font does not change.

Here's a more contrived yet more illustrative example:

(see "html_2.txt", "qtbug_2.png" and "explanations.png" in the attachments)