Diff pair Via gap, overruled by "Via gap same as trace gap"

Description

When routing Diff pairs, the via gap will stay the same as trace gap, even when using seperate rules. Turns out the checkbox in "Use Custom values" will override the setting. I would expect the checkbox to only be active when custom rules are selected. Please see attached video.

Steps to reproduce

KiCad Version

Application: KiCad PCB Editor

Version: 6.0.7-unknown-nightly-202208180417, release build

Libraries:
	wxWidgets 3.0.5
	libcurl/7.81.0 OpenSSL/3.0.2 zlib/1.2.11 brotli/1.0.9 zstd/1.4.8 libidn2/2.3.2 libpsl/0.21.0 (+libidn2/2.3.2) libssh/0.9.6/openssl/zlib nghttp2/1.43.0 librtmp/2.3 OpenLDAP/2.5.12

Platform: Linux 5.15.0-46-generic x86_64, 64 bit, Little endian, wxGTK, ubuntu, x11

Build Info:
	Date: Aug 18 2022 04:17:41
	wxWidgets: 3.0.5 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
	Boost: 1.74.0
	OCC: 7.5.2
	Curl: 7.81.0
	ngspice: 36
	Compiler: GCC 11.2.0 with C++ ABI 1016

Build settings:
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON