I'm a bit confused and I think there's some miscommunication going on between you and your employer.
I wonder if your employer began with a relaxed and reassuring approach, but now feels you are taking the piss and not prioritising work during working time. I don't think it's necessarily a breastfeeding thing, I think it might be a parenting-whilst-working thing.
Different employers have different approaches (and different line managers within them have different approaches too), and I think the past 18 months have hugely blurred everyone's boundaries about whether you can do both at once.
My own take is that after going above and beyond to keep working whenever my previously-sufficient childcare arrangements fell through because covid, I'm happy to expect a bit more flexibility than I had before. OTOH I know people who've decided not to sort any childcare for their toddler whilst wfh, basically to save money, and I think that's just cheeky. You can't really do both.
My 2-3yo could be parked in front of cbeebies for a bit to allow me to work. Sometimes it was great; sometimes she needed more input and my ability to work (lone parent) was v compromised. Often when I was on a meeting ie. more interesting than Octonauts, she'd come over and demand the breast and even though I'd long since cut her down to morning and bedtime, instilled good nursing manners etc I sometimes went with it to have an uninterrupted and complicated conversation. At her age and with her "normal" bf, it wasn't about hunger or pumping or pre-emptively feeding at convenient moments, it was her desperately trying to connect with her mum, who was looking after her and ignoring her.
My work tolerated it as an exceptional, extenuating circumstance, and knowing how I was working to mitigate the impact, and because in the long story of my career it's a blip and they'd be silly to lose me over it. But they also knew I wasn't choosing to have her around whilst working, which makes a huge difference. You're being evasive about your arrangements here so it's hard to guess whether your work feels the same way.
If someone else is caring for your child other than when the breast is required... tricky. I fed on demand until mine went to full-time childcare at 13 and 16 months, but if I left them in someone else's care younger than that i simply wasn't available to feed. DD took an expressed bottle at 4 months, DS always just waited for me to come back. I wasn't in the home though- impossible to ask a baby to wait when they know mummy is just the other side of that door.