I experienced this and replaced the keyboard physically on my same as yours rMBP. Unlikely OCLP.I'm still able to use the keys, but need to hold them down for a very long time before the character appears. Is there any chance this is related to the OCLP Ventura patching? It was working fine before I upgraded from Monterey.
Anyone else experiencing this?
Likely new keyboard (not easy) or at least open and clean/replace the plastic/scissors mechanism (easy) for the malfunctioning keys. There are Youtube videos galore for that type of thing..