Yep, done that too. Cable Matter's adapter has used two different chips from Synaptics over its lifetime. The older one the VMM6100 required a special firmware and a special EDID to work.
It has taken then a month or so to try and copy what worked about that firmware to this new VMM7100 chip, for some reason the same solution they expected to work wasn't doing it. But now they managed to provide a firmware only for the 7100 that no longer requires the EDID as well.
Have tried both EDIDs, in full and in pieces of what they changed to my monitor and it either again removes all choices above 60hz, or sometimes leaves all the choices but anything above 60hz falls back to 4:2:2.
CM has done a great job with this, if they could have provided this with only an EDID profile, I think they absolutely would have, as some customers have to jump through big hoops to be able to update the firmware on these adapters as it can only be done in Windows, and the 6100 only on a Windows machine that has a USB-C with DP port, which most Mac users do not have access to.
So I think they're doing some serious work in the firmware to get around the roadblocks Apple has set up.