Non FDG avid lesion seen in liver 8 months after Whipple surgery

My dad ( 73) had his Whipple's surgery in June 2023 for a stage III PDAC with a clear margin and 0 lymph node positive.
Had a scan in November which came up clean with mild ascites. He recently had another Pet/CT scan and the findings were:
1. An ill-defined non FDG avid hypodense lesion noted in the right lobe of segment VII measuring 1.7 x 1.1 cm in size.
2. Moderate ascites noted with evidence of free fluid in perihepatic and perisplenic spaces and bilateral pleural effusions and peritoneal thickening.
They drained around 40 ml fluid from abdomen and chest area and have sent it for cytology testing. For the lesion in liver, they have done an MRI and both these results are awaited.
I would want to know what is the meaning of these 2 new findings. Has the cancer recurred? The doctor told my parents it didn't glow in the pet scan which is good but still needed MRI to know what's going on.
Could the lesion be an inflammation or infection? My dad is in general feeling really good and is having a good appetite and feeling energetic.
Anyone with an experience with a similar result?
Appreciate any opinion on this.