Before @modifiedequitation erased all their posts other than the original post, I’m sure they wrote that they just found out the head trainer was evicting Molly. That makes me think it’s possible the head trainer got wind of this and other irregularities by Molly already. If Molly is on the way out, there is no need to confront her on this, but be very careful if you ever end up at the same barn as her in future.
On the other hand I just picked up the fact that you saw these photos last winter and only now are wondering if you should say anythung. Were Molly or her assistant given direction by your trainer to exercise or ride your horse during lockdown? That’s the first thing I’d check if it was still last winter.
You could mention it to your trainer now in the vein of “I’m glad she’s going because…” but honestly if you saw the photos 6 months ago, said nothing, and have no reason to think it’s ongoing past lockdown then it doesn’t sound like you really were that worried.
If my barn was on lockdown and I couldn’t ride, I wouldn’t be too upset to see my safe mare getting some appropriate attention. I’d like to be kept informed though.