I'm using HeidiSQL 188.8.131.5276 with Fedora 35 (KDE Plasma 5.24.4) and Wine 7.5.
GUI font: <Default system font> Style theme: Windows
When I start HeidiSQL, all is fine. However, when I do anything that pops up a window, like checking if there is an update or open the Preferences, the font suddenly changes to bold. The connection/database box font immediately changes, the grid cell font changes when I hover over them.
It does not matter which Windows version I select in "winecfg", or if I change any of "CSMT", "VAAPI", "Hide Wine version" or "Enable GTK3 Theming" settings in the winecfg "Staging" tab, or if I change the font to, say, Arial with size 10 in the Preferences (to make sure that Tahoma is not used, since apparently there are issues with that font).
I'm hoping that this is a known issue for which a solution exists.