InDesign does not handle a nukta with Tamil script
The Tamil Unicode block does not contain a nukta, for languages written in Tamil script that need a nukta there are two characters in the Grantha block that can (possibly) be used.
U+1133B COMBINING BINDU BELOW
U+1133C GRANTHA SIGN NUKTA
Dotted circles are shown, and left vowels are not always re-ordered.
This is with InDesign 16.1 on Windows 10 Dev channel of Insider Preview
Edition Windows 10 Pro Insider Preview
Installed on 2021-03-30
OS build 21343.1000
Experience Windows 10 Feature Experience Pack 321.7401.0.3
The files withharfbuzz.png (HarfBuzz enabled https://community.adobe.com/t5/indesign/script-for-enabling-harfbuzz-workflow-in-indesign/m-p/11319835) and worldready.png (Lipika) show how InDesign displays the text. The file chrome.png shows the result (which is desired) from the Chrome browser, also on Windows 10.
The codepoints, font, and additional data files used are on another bug report
Note that the display of text in this bug report is similar but not exactly the same as with InDesign.
Bobby de Vos commented
I did not test InDesign with other font lookup options as mentioned in the Microsoft beg report.