This definitely sounds like a material change to your working conditions. Childcare aside, you previously didn't have to travel to the office, now you do. That's a change.
This is exactly what I think, too. It's a significant material change.
Was the pre-pandemic arrangement written into your contract, OP? If so, it can't just be changed on the whim of your manager. Even if it wasn't a contractual arrangement, it sounds like it may have been established by "custom and practice" and they should be negotiating any change.
As this change occurred while you were on mat leave, it may be worth talking to "Pregnant Then Screwed" pregnantthenscrewed.com/ and see what they say. And there are some knowledgeable people on the employment matters board on here.
Like a PP, I get sick of MNers posting about how much worse it is for other groups of workers when someone has an issue of this. People arrange their lives around the requirements of their work, and making changes like this really fucks around with people's lives.
I wonder what your manager's boss thinks of this? If they're reasonable and approachable, it might be worth speaking to them directly. I once had a manager who was fond of bringing in bonkers working practices. Every time it happened, we went straight to the next in line who basically told them not to be such an arse.
(They ended up being put on capability and were on their way out, but got caught out not disclosing a conflict of interest, was demoted and moved to the far side of the county, and flounced off in a huff, which was a very happy day!)