Set both texture format overrides to false by default

doc/classes/ProjectSettings.xml

@@ -2613,10 +2613,12 @@
 		</member>
 		<member name="rendering/textures/vram_compression/import_etc2_astc" type="bool" setter="" getter="" default="false">
 			If [code]true[/code], the texture importer will import VRAM-compressed textures using the Ericsson Texture Compression 2 algorithm for lower quality textures and normal maps and Adaptable Scalable Texture Compression algorithm for high quality textures (in 4x4 block size).
+			[b]Note:[/b] This setting is an override. The texture importer will always import the format the host platform needs, even if this is set to [code]false[/code].
 			[b]Note:[/b] Changing this setting does [i]not[/i] impact textures that were already imported before. To make this setting apply to textures that were already imported, exit the editor, remove the [code].godot/imported/[/code] folder located inside the project folder then restart the editor (see [member application/config/use_hidden_project_data_directory]).
 		</member>
-		<member name="rendering/textures/vram_compression/import_s3tc_bptc" type="bool" setter="" getter="" default="true">
+		<member name="rendering/textures/vram_compression/import_s3tc_bptc" type="bool" setter="" getter="" default="false">
 			If [code]true[/code], the texture importer will import VRAM-compressed textures using the S3 Texture Compression algorithm (DXT1-5) for lower quality textures and the BPTC algorithm (BC6H and BC7) for high quality textures. This algorithm is only supported on PC desktop platforms and consoles.
+			[b]Note:[/b] This setting is an override. The texture importer will always import the format the host platform needs, even if this is set to [code]false[/code].
 			[b]Note:[/b] Changing this setting does [i]not[/i] impact textures that were already imported before. To make this setting apply to textures that were already imported, exit the editor, remove the [code].godot/imported/[/code] folder located inside the project folder then restart the editor (see [member application/config/use_hidden_project_data_directory]).
 		</member>
 		<member name="rendering/textures/webp_compression/compression_method" type="int" setter="" getter="" default="2">

servers/rendering_server.cpp

@@ -2870,7 +2870,10 @@ TypedArray<StringName> RenderingServer::_global_shader_parameter_get_list() cons
 }
 
 void RenderingServer::init() {
-	GLOBAL_DEF_RST("rendering/textures/vram_compression/import_s3tc_bptc", true);
+	// These are overrides, even if they are false Godot will still
+	// import the texture formats that the host platform needs.
+	// See `const bool can_s3tc_bptc` in the resource importer.
+	GLOBAL_DEF_RST("rendering/textures/vram_compression/import_s3tc_bptc", false);
 	GLOBAL_DEF_RST("rendering/textures/vram_compression/import_etc2_astc", false);
 
 	GLOBAL_DEF("rendering/textures/lossless_compression/force_png", false);