Differences of estimated time in AI Denoise

I have been using AI denoising since its first appearance until today. I don't know why, suddenly some files take much longer to denoise than before. Until now it took 10-15 seconds for EACH FILE (raw from Canon R6), now some files take as the same time as previous and some take about two minutes. I didn't change anything in my workflow, the files are exactly the same, I didn't update the drivers or the program (I updated it later, but nothing changed). My graphics card is RTX 8gb.

What happened?