...under certain conditions, such as when the size changes. The recursive layer itself will likely depend on the texture backing the layer when rendering. Typically, the fragment shader samples it. To make this work, in recursive mode there are two backing textures. There are two problems for recursive mode in the Qt 6 layer implementation. (that in in some ways works quite differently from Qt 5, due to the QRhi migration) 1. When new backing buffers are needed, for example because the item size changes, immediately releasing the main backing texture in favor of a new texture that is correctly sized but has uninitialized content is not ideal, and is not what Qt 5 was doing. Qt 5 continued to use the previous OpenGL texture when rendering for the first time after a size change. As in, exposing the old texture as the layer's backing texture, thus a recursive shader effect was sampling that in the shader. (that the size of that input texture is technically incorrect now is usually not a visible issue, and comes by design with recursive mode) Only once rendering to the new texture has been done for the first time is the old texture released. The new one (which we just rendered into) then takes over as the backing texture returned from rhiTexture() (or the equivalent in Qt 5). Make the Qt 6 implementation of layers to be identical to Qt 5 in this regard. 2. There is an additional problem in the very first frame. Neither Qt 5 nor 6 clears the main backing texture. Because rendering to it does that anyway. In recursive mode however, the very first frame will also sample the texture. And the texture has uninitialized content at that point, similarly to problem #1. The result is that a non-live, recursive effect source exhibits either artifacts, magenta (Metal) content, or just happens to look correct (so not a visible issue usually with Qt 5 and OpenGL) With live: true (the default) this issue is hidden, although the garbage my still flicker in from the first frame. Do an explicit clear now, so the first frame does not sample potential garbage. Pick-to: 6.10 6.9 6.8 Fixes: QTBUG-112355 Change-Id: Ic9d2b0dc4aa6ab1e99d456bcce48ffa9ffbfecfe Reviewed-by: Andy Nichols <andy.nichols@qt.io>