The main problem with LGPLv3 is the anti-tivoization clause. That means you should basically provide the end user a way to replace the Qt libraries with their own. On embedded systems this can mean headaches for companies releasing commercial products.

More details: https://embeddeduse.com/2016/04/10/using-qt-5-6-and-later-un...

Qt from 4.8(?) To 5.6 offered an LGPL2 license too but after that it's mostly LGPLv3 i think.