Purebasic 6.03 is compiled against library: libwebkit2gtk-4.0.so.37
so if Purebasic wouldn't start go to add/remove software and search for libwebkit2gtk-4.0-37
if that package is not installed (by default not) > install it and Purebasic will start.
I've checked this on Bookworm and Purebasic starts