RAW photos from EOS Rebel T7 back to darkening again

[Tintype_18]

Thought this was over and done but RAW photos taken yesterday will darken after a couple of seconds. JPEG photos are not affected. Many photos taken before at other times are OK but the situation is back. The photos were taken in bright outdoor light if that would make a difference. I went to manual on some (faster lens speed and increased ISO) but no change. Your help and advice is welcome.

[Waddizzle]

I use PS/LR for post processing of images.  But I use DPP to browse through folders of image files, instead of File Explorer, prior to importing them into LR.