2) Avoid using dynamic links (render AE-comp as video first, then import into PP), if can't avoid - try nesting. 3) Don't use big/super-sized still images, downscale first; if can't avoid - nesting may help sometimes 4) Try to create new project, import old one, then export 5) Close PP, or even reboot a PC before starting export. Don't use memory hungry apps while exporting (like Chrome with many tabs opened) 6) Check for free space on a cache and export disks 7) Use short and simple file/directory naming (aA-zZ_0-9 only, no spaces) 8) Turn off GPU overclocking (if there are any) 9) Try to Export to h265 instead of h264 (likely take less RAM/VRAM)
10) If you are using external storage, and render will take long time, make sure it won't go sleep mode in the middle of rendering
If this doesn't work: go to the affected clip, cut (CTRL/CMD+X) the Lumetri Effect. Then, either paste the effect back on or re-apply another instance of the Lumetri Effect (which means you need to redo the color correction/grade).
Also, could it be that there is a LUT applied to Lumetri? Could this be the source of your problem?