I expect that batteries are exempted from the Right to Repair law but I complained to Icom anyway. Their reply was as follows:
"Unfortunately Icom Japan could no longer source component/materials to continue to manufacture the BP275/M91D battery.
There have been major global issues with electronic component supply chain [for manufacture] effecting viability.
M91D went out of production in 2016.
I understand far from ideal, but if it helps at all - I am happy to offer you our latest handheld DSC/AIS/VHF at a discounted price."
2016 would mean that the M91D was discontinued more than seven years ago, which is one of the cut-off points mentioned in the Right to Repair law. The other one is ten years but I don't have the energy to wade through the law to see which, if any, is applicable to batteries. I think getting a secondhand battery on eBay is the way to go. I'm not tempted by a new M94DE at a discount.