The "Export Frame" button should have options for bit depth
When you quickly export a frame, if you use formats like PNG or TIFF, it by default outputs at 8bit. However, sometimes we may be using higher bit depth footage and want to preserve that on export. Previously, we could do that with the export panel, although it was slower, but with the new panel, that has become much harder to work with for single frame exports, since the playhead doesn't match the position of the playhead in the sequence editor.
Another option that may be useful for some people would be to disable color management for these screencaps, or other exports, so that if you're working with HDR footage, you could bypass premiere's HDR-to-SDR tonemapping and export in the native EOTF without reinterpreting the footage first. This can be useful if you want to color grade the HDR screenshots or footage to SDR in other software.
These options could be hidden away in preferences, or sequence/project settings, since they wouldn't be something everybody would be interested in using, but they would be extremely helpful for those that need them.
Andy Gilleand commented
Lately, I've been using DPX (with help of the still-exporter extension for batch export), which does at least encode the screenshot at 10bit, but even with a 10bit source, I've compared a DPX screenshot with a manually exported 16bit TIFF, and there are minor errors, even with a 10bit ProRes source file. The errors are too small for a human to see without manipulation, but if I plan to use these screenshots for generating HDR metadata and other statistics, more precision is better to have. EXR is another format that has high bit depth, but it converts the source into a linear 32bit color space, which can be useful in certain applications, but I need precise RGB values that match the source, so no EOTF conversions.
So I still think there's a reason to allow higher bit depth formats for the export frame button. At the very least, give us control over the presets used for that button, since the new premiere seems to be so focused on presets for export. So it would fit nicely with the new workflow.