Monstera rotting after thrips?

Some weeks ago I realised I was under a pretty heave thrips attack. Followed some advice I found online by spraying the plant with a green soap/rapeseed oil mix. Seems I got rid of the thrips.

One of the leaves were pretty heavily damaged, but the rest seemed ok. Until I just now noticed some black spots starting to emerge. Some Googling made me think i’d gotten root rot.

Started repotting, but the roots didn’t seem all too bad compared to images online? They might look a bit slimy in the picture, but I’ve just showered them, so i think they’re just wet? If i scrape of the brown, they’re green underneath. They don’t feel squishy.

However, I wonder if the stem shows signs of rotting? And I noticed the discoloring on the stem seemed to under and slightly above where the badly thrips-damaged leaf connects to the main stem. Could it be that the leaf has been infected and that the infection has spread to the rest of the plant through it? Should I cut it of where illustrated and consequently loose all the roots? Or is it more probable that it’s a root rot? Or just black spots from the plant reacting to the rapeseed/green soap cure?

The plant sits in a huge west facing window in Oslo, Norway. It gets plenty of light this time of year, but hasn’t had too much in winter. I water the plant when the uppermost inches feel dry, and the soil was with a decent amount of perlite. However, may have overwatered a bit when showering it for getting rid of thrips. But also let it drain after.

Any advice would be hugely appreciated! Thank you in advance.